FEATURES
■Clock-Tunable Cutoff Frequency
■1mV DC Offset (Typical)
■80dB CMRR (Typical)
■Internal or External Clock
■50μVRMS Clock Feedthrough
■100:1 Clock-to-Cutoff Frequency Ratio
■95μVRMS Total Wideband Noise
■0.01% THD at 2VRMS Output Level
■50kHz Maximum Cutoff Frequency
■Cascadable for Faster Roll-Off
■Operates from ±2.375 to ±8V Power Supplies
■Self-Clocking with 1 RC
APPLICATIOUS
■Audio
■Strain Gauge Amplifiers
■Anti-Aliasing Filters
■Low Level Filtering
■Digital Voltmeters
■60Hz Lowpass Filters
■Smoothing Filters
■Reconstruction Filters
LTC1063
DC Accurate, Clock-Tunable
5th Order Butterworth
Lowpass Filter
DESCRIPTIOU
The LTC1063 is the first monolithic filter providing both clock-tunability, low DC output offset and over 12-bit DC accuracy. The frequency response of the LTC1063 closely approximates a 5th order Butterworth polynomial. With appropriate PCB layout techniques the output DC offset is typically 1mV and is constant over a wide range of clock frequencies. With ±5V supplies and ±4V input voltage range, the CMR of the device is 80dB.
The filter cutoff frequency is controlled either by an internal or external clock. The clock-to-cutoff frequency ratio is 100:1. The on-board clock is power supply independent,
and it is programmed via an external RC. The 50μVRMS clock feedthrough is considerably reduced over existing
monolithic filters.
The LTC1063 wideband noise is 95μVRMS, and it can process large AC input signals with low distortion. With
±7.5V supplies, for instance, the filter handles up to 4VRMS (92dB S/N ratio) while the standard 1kHz THD is below 0.02%; 80dB dynamic ranges (S/N +THD) is obtained with input levels between 1VRMS and 2.3VRMS.
The LTC1063 is available in 8-pin miniDIP and 16-pin SOL. For a linear phase response, see LTC1065 data sheet.
TYPICAL APPLICATIOU
2.5kHz 5th Order Lowpass Filter Frequency Response
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VIN** 1 |
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8 |
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2 |
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7 |
VOUT |
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LTC1063 |
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3 |
6 |
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5V |
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–5V |
4 |
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5 |
0.1μF |
(dB)GAIN |
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0.1μF |
*19.1k |
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200pF* |
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*SELF-CLOCKING SCHEME
**IF THE INPUT VOLTAGE CAN EXCEED V+,
CONNECT A SIGNAL DIODE BETWEEN PIN 1 AND V+.
1063 TA01
10
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
1 |
10 |
100 |
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FREQUENCY (kHz) |
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1063 TA02
1
LTC1063
ABSOLUTE WAXIWUW |
RATIUGS |
Total Supply Voltage (V + to V –) .......................... |
16.5V |
Power Dissipation............................................. |
400mW |
Voltage at Any Input .... (V – – 0.3V) ≤ VIN ≤ (V+ + 0.3V) |
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Burn-In Voltage ...................................................... |
16V |
Operating Temperature Range ............... |
– 40°C to 85°C |
Storage Temperature Range ................ |
– 65°C to 150°C |
Lead Temperature (Soldering, 10 sec)................. |
300°C |
PACKAGE/ORDER IUFORWATIOU
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TOP VIEW |
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VIN |
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VOS ADJ |
1 |
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8 |
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GND |
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VOUT |
2 |
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7 |
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V– |
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V+ |
3 |
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6 |
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CLK OUT |
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CLK IN |
4 |
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5 |
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J8 PACKAGE
8-LEAD CERAMIC DIP
N8 PACKAGE
8-LEAD PLASTIC DIP
TJMAX = 150°C, θJA = 100°C/W (J) TJMAX = 100°C, θJA = 110°C/W (N)
ORDER PART
NUMBER
LTC1063CN8
LTC1063CJ8
LTC1063MJ8
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TOP VIEW |
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NC |
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1 |
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16 |
VOS ADJ |
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VIN |
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2 |
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15 |
NC |
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GND |
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3 |
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14 |
VOUT |
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NC |
4 |
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13 |
NC |
V– |
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V+ |
5 |
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12 |
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NC |
6 |
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11 |
NC |
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NC |
7 |
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10 |
NC |
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CLK OUT |
8 |
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9 |
CLK IN |
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S PACKAGE
16-LEAD PLASTIC SOL
TJMAX = 100°C, θJA = 85°C/W
ORDER PART
NUMBER
LTC1063CS
ELECTRICAL CHARACTERISTICS
VS = ±5V, fCLK = 500kHz, fC = 5kHz, RL = 10k, TA = 25°C, unless otherwise specified.
PARAMETER |
CONDITIONS |
MIN |
TYP |
MAX |
UNITS |
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Clock-to-Cutoff Frequency Ratio (fCLK /fC) |
±2.375V ≤ VS ≤ ±7.5V |
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100 ± 0.5 |
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Maximum Clock Frequency (Note 1) |
VS = ±7.5V |
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5 |
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MHz |
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VS = ±5V |
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4 |
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MHz |
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VS = ±2.5V |
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3 |
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MHz |
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Minimum Clock Frequency (Note 2) |
±2.5V ≤ VS ≤ ±7.5V, TA < 85°C |
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30 |
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Hz |
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Input Frequency Range |
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0 |
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0.9fCLK |
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Filter Gain |
VS = ±5V, fCLK = 25kHz, fC = 250Hz |
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fIN = 250Hz |
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– 3.5 |
– 3.0 |
– 2.5 |
dB |
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● |
– 3.6 |
– 3.0 |
– 2.4 |
dB |
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VS = ±5V, fCLK = 500kHz, fC = 5kHz |
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fIN = 100Hz |
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0 |
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dB |
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fIN = 1kHz = 0.2fC |
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– 0.06 |
– 0.01 |
0.04 |
dB |
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● |
– 0.075 |
– 0.01 |
0.055 |
dB |
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fIN = 2.5kHz = 0.5fC |
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– 0.09 |
0.16 |
0.41 |
dB |
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● |
– 0.14 |
0.16 |
0.46 |
dB |
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fIN = 4kHz = 0.8fC |
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– 0.5 |
– 0.2 |
0.1 |
dB |
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● |
– 0.6 |
– 0.2 |
0.2 |
dB |
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fIN = 5kHz = fC |
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– 3.5 |
– 3.0 |
– 2.5 |
dB |
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● |
– 3.6 |
– 3.0 |
– 2.4 |
dB |
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fIN = 20kHz = 4fC |
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– 57.5 |
– 60.0 |
– 62.0 |
dB |
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● |
– 57.0 |
– 60.0 |
– 62.5 |
dB |
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2
LTC1063
ELECTRICAL CHARACTERISTICS
VS = ±5V, fCLK = 500kHz, fC = 5kHz, RL = 10k, TA = 25°C, unless otherwise specified.
PARAMETER |
CONDITIONS |
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MIN |
TYP |
MAX |
UNITS |
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Filter Gain |
VS = ±2.375V, fCLK = 500kHz, fC = 5kHz |
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fIN = 1kHz |
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– 0.066 |
0.004 |
0.074 |
dB |
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● |
– 0.081 |
0.004 |
0.089 |
dB |
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fIN = 2.5kHz |
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– 0.24 |
0.16 |
0.56 |
dB |
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● |
– 0.29 |
0.16 |
0.61 |
dB |
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fIN = 4kHz |
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– 0.6 |
– 0.2 |
0.2 |
dB |
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● |
– 0.7 |
– 0.2 |
0.3 |
dB |
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fIN = 5kHz |
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– 3.5 |
– 3.0 |
– 2.5 |
dB |
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● |
– 3.6 |
– 3.0 |
– 2.4 |
dB |
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Clock Feedthrough |
±2.375 ≤ VS ≤ ±7.5V |
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50 |
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μVRMS |
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Wideband Noise (Note 3) |
±2.375 ≤ VS ≤ ±7.5V, 1Hz < f < fCLK |
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100 |
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μVRMS |
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THD + Wideband Noise (Note 4) |
VS = ±7.5V, fC |
= 20kHz, fIN = 1kHz, |
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–80 |
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dB |
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1VRMS ≤ VIN ≤ 2.3VRMS |
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Filter Output ± DC Swing |
VS = ±2.375V |
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1.6/– 2.0 |
1.7/– 2.2 |
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V |
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● |
1.4/– 1.8 |
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V |
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VS = ±5V |
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4.0/– 4.5 |
4.3/– 4.8 |
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V |
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● |
3.8/– 4.3 |
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V |
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VS = ±7.5V |
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6.5/– 7.0 |
6.8/– 7.3 |
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V |
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● |
6.3/– 6.8 |
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V |
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Input Bias Current |
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10 |
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nA |
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Dynamic Input Impedance |
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800 |
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MΩ |
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Output DC Offset (Note 5) |
VS = ±2.375V |
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2 |
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mV |
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VS = ±5V |
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0 |
±5 |
mV |
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VS = ±7.5V |
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– 4 |
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mV |
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Output DC Offset Drift |
VS = ±2.375V |
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10 |
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μV/°C |
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VS = ±5V |
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20 |
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μV/°C |
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VS = ±7.5V |
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25 |
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μV/°C |
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Self-Clocking Frequency (fOSC) |
R (Pin 4 to 5) = 20k, C (Pin 5 to GND) = 470pF |
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VS = ±2.375V |
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99 |
105 |
112 |
kHz |
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LTC1063CN, CS, CJ |
● |
95 |
103 |
111 |
kHz |
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LTC1063MJ |
● |
92 |
100 |
108 |
kHz |
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VS = ±5V |
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102 |
108 |
114 |
kHz |
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LTC1063CN, CS, CJ |
● |
98 |
106 |
114 |
kHz |
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LTC1063MJ |
● |
97 |
105 |
114 |
kHz |
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VS = ±7.5V |
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104 |
110 |
116 |
kHz |
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LTC1063CN, CS, CJ |
● |
101 |
109 |
116 |
kHz |
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LTC1063MJ |
● |
100 |
108 |
116 |
kHz |
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External CLK Pin Logic Thresholds |
VS = ±2.375V |
Min Logical “1” |
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1.43 |
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V |
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Max Logical “0” |
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0.47 |
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V |
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VS = ±5V |
Min Logical “1” |
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3 |
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V |
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Max Logical “0” |
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1 |
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V |
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VS = ±7.5V |
Min Logical “1” |
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4.5 |
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V |
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Max Logical “0” |
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1.5 |
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V |
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Power Supply Current |
VS = ±2.375V, fCLK = 500kHz |
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2.7 |
4.0 |
mA |
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LTC1063CN, CS, CJ |
● |
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5.5 |
mA |
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LTC1063MJ |
● |
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6.0 |
mA |
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VS = ±5V, fCLK = 500kHz |
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5.5 |
8 |
mA |
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LTC1063CN, CS, CJ |
● |
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11 |
mA |
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LTC1063MJ |
● |
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12 |
mA |
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VS = ±7.5V, fCLK = 500kHz |
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7.0 |
11 |
mA |
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LTC1063CN, CS, CJ |
● |
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14.5 |
mA |
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LTC1063MJ |
● |
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16.0 |
mA |
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3
LTC1063
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range.
Note 1: The maximum clock frequency criterion is arbitrarily defined as: The frequency at which the filter AC response exhibits ³ 1dB of gain peaking.
Note 2: At limited temperature ranges (i.e., TA £ 50°C) the minimum clock frequency can be as low as 10Hz. The minimum clock frequency is arbitrarily defined as: the clock frequency at which the output DC offset changes by more than 1mV.
Note 3: The wideband noise specification does not include the clock feedthrough.
Note 4: To properly evaluate the filter’s harmonic distortion an inverting output buffer is recommended as shown in the Test Circuit. An output buffer is not necessarily needed when measuring output DC offset or wideband noise.
Note 5: The output DC offset is optimized for ±5V supply. The output DC offset shifts when the power supplies change; however this phenomenon is repeatable and predictable.
TYPICAL PERFORWAUCE CHARACTERISTICS
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Output Offset vs Clock, |
Output Offset vs Clock, |
Self-Clocking Frequency vs R |
Low Clock Rates |
Medium Clock Rates |
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110 |
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50 |
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5 |
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100 |
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LTC1063 |
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45 |
VS = ±5V |
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4 |
VS = ±7.5V |
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90 |
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40 |
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3 |
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4 |
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5 |
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A: TA = 25°C |
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TO45 (kΩ) |
80 |
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R |
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OFFSET(mV) |
35 |
B: TA = 85°C |
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OFFSET(mV) |
2 |
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60 |
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C = 200pF |
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C |
25 |
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0 |
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70 |
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30 |
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1 |
VS = ±5V |
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PINSR |
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fOSC 1/RC |
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OUTPUT |
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OUTPUT |
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40 |
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15 |
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–2 |
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50 |
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20 |
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–1 |
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30 |
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10 |
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–3 |
VS = ±2.5V |
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20 |
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5 |
B |
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–4 |
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10 |
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0 |
A |
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–5 |
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100 |
300 |
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500 |
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110 |
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210 |
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500 |
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1000 |
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10 |
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0 |
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FREQUENCY (kHz) |
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EXTERNAL CLOCK FREQUENCY (Hz) |
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EXTERNAL CLOCK FREQUENCY (kHz) |
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1063 G01 |
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1063 G02 |
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1063 G03 |
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Gain vs Frequency; VS = ±2.5V |
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Gain vs Frequency; VS = ±5V |
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Gain vs Frequency; VS = ±7.5V |
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10 |
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10 |
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10 |
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0 |
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0 |
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0 |
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D |
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–10 |
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–10 |
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–10 |
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A |
B |
C |
E |
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–20 |
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–20 |
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–20 |
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(dB) |
–30 |
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A |
B |
C |
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(dB) |
–30 |
A |
B C |
D |
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(dB) |
–30 |
A. fCLK = 1MHz |
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–40 |
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–40 |
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–40 |
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GAIN |
A. fCLK = 0.5MHz |
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GAIN |
B. fCLK = 2MHz |
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GAIN |
C. fCLK = 3MHz |
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–50 |
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–50 |
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–50 |
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A. fCLK = 1MHz |
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B. fCLK = 2MHz |
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–60 |
B. fCLK = 1MHz |
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–60 |
C. fCLK = 3MHz |
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D. fCLK = 4MHz |
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–60 E. fCLK = 5MHz |
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C. fCLK = 2MHz |
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D. fCLK = 4MHz |
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–70 |
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|
|
|
–70 |
|
|
|
|
–70 |
|
|
|
|
|
||
|
VIN = 750mVRMS |
|
|
|
|
|
|
VIN = 1.5VRMS |
|
|
|
|
|
|
|
|
|
|||
|
–80 |
|
|
|
|
|
|
–80 |
|
|
|
|
–80 |
VIN = 2.5VRMS |
|
|
|
|
||
|
TA = 25°C |
|
|
|
|
|
|
TA = 25°C |
|
|
|
|
TA = 25°C |
|
|
|
|
|||
|
–90 |
|
|
|
|
|
|
–90 |
|
|
|
|
–90 |
|
|
|
|
|||
|
|
10 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||
|
1 |
|
|
|
100 |
200 |
|
1 |
10 |
|
100 |
200 |
|
1 |
10 |
|
|
100 |
200 |
|
INPUT FREQUENCY (kHz) |
INPUT FREQUENCY (kHz) |
INPUT FREQUENCY (kHz) |
1063 G04 |
1063 G05 |
1063 G06 |
4
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