FEATURES
Dual Matched PNP Transistor
Low Offset Voltage: 100 V Max
Low Noise: 1 nV/√Hz @ 1 kHz Max
High Gain: 100 Min
High Gain Bandwidth: 190 MHz Typ
Tight Gain Matching: 3% Max
Excellent Logarithmic Conformance: r
GENERAL DESCRIPTION
The MAT03 dual monolithic PNP transistor offers excellent
parametric matching and high frequency performance. Low
√
noise characteristics (1 nV/
(190 MHz typical), and low offset voltage (100 µV max), makes
the MAT03 an excellent choice for demanding preamplifier applications. Tight current gain matching (3% max mismatch) and
high current gain (100 min), over a wide range of collector current, makes the MAT03 an excellent choice for current mirrors.
A low value of bulk resistance (typically 0.3 Ω) also makes the
MAT03 an ideal component for applications requiring accurate
logarithmic conformance.
Hz max @ 1 kHz), high bandwidth
⯝ 0.3 ⍀ typ
BE
Dual PNP Transistor
MAT03
PIN CONNECTION
TO-78
(H Suffix)
Each transistor is individually tested to data sheet specifications.
Device performance is guaranteed at 25°C and over the extended
industrial and military temperature ranges. To ensure the longterm stability of the matching parameters, internal protection
diodes across the base-emitter junction clamp any reverse baseemitter junction potential. This prevents a base-emitter breakdown
condition that can result in degradation of gain and matching
performance due to excessive breakdown current.
REV. C
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
Absolute maximum ratings apply to both DICE and packaged devices.
2
Rating applies to TO-78 not using a heat sink and LCC; devices in free air only. For
TO-78, derate linearly at 6.3 mW/°C above 70°C ambient temperature; for LCC,
derate at 7.8 mW/°C.
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the MAT03 features propriety ESD protection circuitry, permanent damage may occur
on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions
are recommended to avoid performance degradation or loss of functionality.
1
) . . . . . . . . . . . . . . . . . . . 36 V
) . . . . . . . . . . . . . . . . . 36 V
CEO
) . . . . . . . . . . . . . . . . . 36 V
CC
) . . . . . . . . . . . . . . . . . . . 36 V
2
. . . . . . . . . . . . . . . 500 mW
REV. C
–3–
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MAT03
–Typical Performance Characteristics
TPC 1. Current Gain vs.
Collector Current
TPC 4. Base-Emitter Voltage
vs. Collector Current
TPC 2. Current Gain
vs. Temperature
TPC 5. Small-Signal Input Resistance
) vs. Collector Current
(h
ie
TPC 3. Gain Bandwidth vs.
Collector Current
TPC 6. Small Signal Output Conductance (h
) vs. Collector Current
oe
–4–
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Page 5
MAT03
TPC 7. Saturation Voltage
vs. Collector Current
TPC 10. Total Noise vs. Collector Current
TPC 8. Noise Voltage Density
vs. Frequency
TPC 11. Collector-Base Capacitance vs. V
TPC 9. Noise Voltage Density
CB
REV. C
–5–
Page 6
MAT03
Figure 1. SPICE or SABER Model
APPLICATIONS INFORMATION
MAT03 MODELS
The MAT03 model (Figure 1) includes parasitic diodes D
3
through D6. D1 and D2 are internal protection diodes that prevent
zenering of the base-emitter junctions.
The analysis programs, SPICE and SABER, are primarily used
in evaluating the functional performance of systems. The models
are provided only as an aid in using these simulation programs.
MAT03 NOISE MEASUREMENT
All resistive components (Johnson noise, e
= 0.13√R nV/√Hz, where R is in kΩ) and semiconductor
e
n
2
= 4kTBR, or
n
junctions (shot noise, caused by current flowing through a
junction, produces voltage noise in series impedances such as
transistor-collector load resistors, I
= 0.566 √I pA/√Hz where
n
I is in µA) contribute to the system input noise.
Figure 2 illustrates a technique for measuring the equivalent input noise voltage of the MAT03. 1 mA of stage current is used
Figure 2. MAT03 Voltage Noise Measurement Circuit
–6–
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Page 7
MAT03
to bias each side of the differential pair. The 5 kΩ collector
resistors noise contribution is insignificant compared to the voltage noise of the MAT03. Since noise in the signal path is referred
back to the input, this voltage noise is attenuated by the gain of
the circuit. Consequently, the noise contribution of the collector load resistors is only 0.048 nV/√Hz. This is considerably
less than the typical 0.8 nV/√Hz input noise voltage of the
MAT03 transistor.
The noise contribution of the OP27 gain stages is also negligible due to the gain in the signal path. The op amp stages
amplify the input referred noise of the transistors to increase the
signal strength to allow the noise spectral density (e
to be measured with a spectrum analyzer. Since we assume
equal noise contributions from each transistor in the MAT03,
the output is divided by √2 to determine a single transistor’s
input noise.
Air currents cause small temperature changes that can appear
as
low frequency noise. To eliminate this noise source, the mea-
× 10000)
in
surement circuit must be thermally isolated. Effects of extraneous
noise sources must also be eliminated by totally shielding the circuit.
SUPER LOW NOISE AMPLIFIER
The circuit in Figure 3a is a super low noise amplifier with
equivalent input voltage noise of 0.32 nV/√Hz. By paralleling
three MAT03 matched pairs, a further reduction of amplifier
noise is attained by a reduction of the base spreading resistance
by a factor of 3, and consequently the noise by √3. Additionally,
the shot noise contribution is reduced by maintaining a high
collector current (2 mA/device) which reduces the dynamic
emitter resistance and decreases voltage noise. The voltage noise
is inversely proportional to the square root of the stage current,
and current noise increases proportionally to the square root of
the stage current. Accordingly, this amplifier capitalizes on
voltage noise reduction techniques at the expense of increasing
the current noise. However, high current noise is not usually
important when dealing with low impedance sources.
REV. C
Figure 3a. Super Low Noise Amplifier
–7–
Page 8
MAT03
This amplifier exhibits excellent full power ac performance,
0.08% THD into a 600 Ω load, making it suitable for exacting
audio applications (see Figure 3b).
Figure 3b. Super Low Noise Amplifier—Total
Harmonic Distortion
LOW NOISE MICROPHONE PREAMPLIFIER
Figure 4 shows a microphone preamplifier that consists of a
MAT03 and a low noise op amp. The input stage operates at a
relatively high quiescent current of 2 mA per side, which reduces
the MAT03 transistor’s voltage noise. The 1/ƒ corner is less than
1 Hz. Total harmonic distortion is under 0.005% for a 10 V p-p
signal from 20 Hz to 20 kHz. The preamp gain is 100, but can be
modified by varying R
or R6 (V
5
OUT/VIN
A total input stage emitter current of 4 mA is provided by Q
The constant current in Q
is set by using the forward voltage of
2
= R5/R6 + 1).
.
2
a GaAsP LED as a reference. The difference between this voltage
and the V
of a silicon transistor is predictable and constant (to
BE
a few percent) over a wide temperature range. The voltage difference, approximately 1 V, is dropped across the 250 Ω resistor
which produces a temperature stabilized emitter current.
CURRENT SOURCES
A fundamental requirement for accurate current mirrors and
active load stages is matched transistor components. Due to the
excellent V
matching (the voltage difference between VBEs
BE
required to equalize collector current) and gain matching, the
MAT03 can be used to implement a variety of standard current
mirrors that can source current into a load such as an amplifier
stage. The advantages of current loads in amplifiers versus
resistors is an increase of voltage gain due to higher impedances, larger signal range, and in many applications a wider
signal bandwidth.
Figure 5 illustrates a cascode current mirror consisting of two
MAT03 transistor pairs.
The cascode current source has a common base transistor in series with the output which causes an increase in output impedance of the current source since V
stays relatively constant.
CE
High frequency characteristics are improved due to a reduction
of Miller capacitance. The small-signal output impedance can
be determined by consulting “h
vs. Collector Current” typical
OF
graph. Typical output impedance levels approach the performance of a perfect current source.
Considering a typical collector current of 100 µA, we have:
ro
=
Q3
1
MHOS
= 1 MΩ
1. 0
µ
Figure 4. Low Noise Microphone Preamplifier
–8–
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Page 9
MAT03
Q2 and Q3 are in series and operate at the same current levels so
the total output impedance is:
RO = hFE roQ3 @ (160)(1 MΩ) = 160 MΩ.
Figure 5. Cascode Current Source
CURRENT MATCHING
The objective of current source or mirror design is generation of
currents that are either matched or must maintain a constant ratio. However, mismatch of base emitter voltages cause output
current errors. Consider the example of Figure 5. If the resistors
and transistors are equal and the collector voltages are the same,
the collector currents will match precisely. Investigating the current matching errors resulting from a nonzero V
as the current error between the two transistors.
∆I
C
, we define
OS
Graph 6b describes the relationship of current matching errors
versus offset voltage for a specified average current I
. Note that
C
since the relative error between the currents is exponentially
proportional to the offset voltage, tight matching is required to
design high accuracy current sources. For example, if the offset
voltage is 5 mV at 100 µA collector current, the current match-
ing error would be 20%. Additionally, temperature effects such
as offset drift (3 µV/°C per mV of V
if Q
and Q2 are not well matched.
1
DIGITALLY PROGRAMMABLE BIPOLAR CURRENT
PUMP
) will degrade performance
OS
The circuit of Figure 7 is a digitally programmable current
pump. The current pump incorporates a DAC08, and a fast
Wilson current source using the MAT03. Examining Figure 7,
the DAC08 is set for 2 mA full-scale range so that bipolar current operation of ±2 mA is achieved. The Wilson current mirror
maintains linearity within the LSB range of the 8-bit DAC08
(±2 mA/256 = 15.6 µA resolution) as seen in Figure 8. A negative feedback path established by Q
regulates the collector cur-
2
rent so that it matches the reference current programmed by the
DAC08.
Collector-emitter voltages across both Q
by D
, with Q3’s collector-emitter voltage remaining constant,
1
and Q3 are matched
1
independent of the voltage across the current source output.
Since Q
maintain the same collector current. D
clamp which prevents Q
buffers Q3, both transistors in the MAT03, Q1 and Q3,
2
from turning off, thereby improving
2
and D3 form a Baker
2
the switching speed of the current mirror. The feedback serves
to increase the output impedance and improves accuracy by reducing the base-width modulation which occurs with varying
collector-emitter voltages. Accuracy and linearity performance
of the current pump is summarized in Figure 8.
Figure 6a. Current Matching Circuit
Figure 6b. Current Matching Accuracy %
vs. Offset Voltage
REV. C
Figure 7. Digitally Programmable Bipolar Current Pump
–9–
Page 10
MAT03
Figure 8. Digitally Programmable Current
Pump—INL Error as Digital Code
The full-scale output of the DAC08, I
of I
REF
256
IFR =
The current mirror output is I
I
REF
I = 2 I
= 2
× I
256
= 2 mA:
– 1.992 mA
OUT
Input Code
256
REF
, and I
OUT
OUT
+
–
(2 mA) – 1.992 mA.
, is a linear function
OUT
= I
I
OUT
I
OUT
REF
= 1, so that if
256
256
DIGITAL CURRENT PUMP CODING
Digital Input
B1 . . . B8Output Current
FULL RANGE1111 1111I = 1.992 mA
HALF RANGE1000 0000I = 0.008 mA
ZERO SCALE0000 0000I = –1.992 mA