Intersil Corporation HSP45102, HSP45102PC-33, HSP45102PC-40, HSP45102SC-40 Datasheet

HSP45102

Data Sheet January 1999 File Number

12-Bit Numerically Controlled Oscillator

The Intersil HSP45102 is Numerically Controlled Oscillator (NCO12) with 32-bit frequency resolution and 12-bit output. With over 69dB of spurious free dynamic range and worst case frequency resolution of 0.009Hz, the NCO12 provides signiﬁcant accuracy for frequency synthesis solutions at a competitive price.

The frequency to be generated is selected from twofrequency control words. A single control pin selects which word is used to determine the output frequency. Switching from one frequency to another occurs in one clock cycle, with a 6 clock pipeline delay from the time that the new control word is loaded until t

Two pins, P0-1, are provided forphase modulation. They are encoded and added to the top two bits of the phase accumulator to offset the phase in 90

The 13-bit output of the Phase Offset Adder is mapped to the sine wave amplitude via the Sine ROM. The output data format is offset binary to simplify interfacing to D/A converters. Spurious frequency components in the output sinusoid are less than -69dBc.

The NCO12 has applications as a Direct Digital Synthesizer and modulator in low cost digital radios, satellite terminals, and function generators.

he new frequency appears on the output.

increments.

2810.6

Features

• 33MHz, 40MHz Versions

• 32-Bit Frequency Control

• BFSK, QPSK Modulation

• Serial Frequency Load

• 12-Bit Sine Output

• Offset Binary Output Format

• 0.009Hz Tuning Resolution at 40MHz

• Spurious Frequency Components <-69dBc

• Fully Static CMOS

• Low Cost

Applications

• Direct Digital Synthesis

• Modulation

• PSK Communications

• Related Products

- HI5731 12-Bit, 100MHz D/A Converter

Ordering Information

TEMP.

PART NUMBER

HSP45102PC-33 0 to 70 28 Ld PDIP E28.6 HSP45102PC-40 0 to 70 28 Ld PDIP E28.6 HSP45102SC-33 0 to 70 28 Ld SOIC M28.3 HSP45102SC-40 0 to 70 28 Ld SOIC M28.3 HSP45102SI-33 -40 to 85 28 Ld SOIC M28.3

RANGE (oC) PACKAGE

PKG.

NO.

Block Diagram

CLK

PO-1

MSB/LSB

SFTEN

SCLK

3-195

FREQUENCY

CONTROL

SECTION

LOAD

TXFR

ENPHAC

SEL_L/M

32 32

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

PHASE

ACCUMULATOR

http://www.intersil.com or 407-727-9207

PHASE

OFFSET

ADDER

13 12

SINE ROM

OUT0-11

Pinout

HSP45102

28 LEAD PDIP, 28 LEAD SOIC

TOP VIEW

OUT6 OUT7 OUT8

OUT9 OUT10 OUT11

GND

SEL_L/M

SFTEN

MSB/LSB

ENPHAC

SCLK

2 3 4 5 6 7 8

9 10 11 12 13 14

OUT5

28 27

OUT4

OUT3

OUT2

OUT1

OUT0

GND

LOAD

TXFR

CLK

GND

Pin Description

NAME TYPE DESCRIPTION

GND Ground P0-1 I Phase modulation inputs (become active after a pipeline delay of four clocks). A phase shift of 0, 90,

CLK I NCO clock. (CMOS level)

SCLK I This pin clocks the frequency control shift register.

SEL_L/M I A high on this input selects the least signiﬁcant 32 bits of the 64-bit frequency register as the input to

SFTEN I The active low input enables the shifting of the frequency register.

MSB/LSB I This input selects the shift direction of the frequency register. A low on this input shifts in the data LSB

ENPHAC I This pin, when low, enables the clocking of the Phase Accumulator. This input has a pipeline delay of

SD I Data on this pin is shifted into the frequency register by the r ising edge of SCLK when SFTEN is low.

TXFR I This active low input is clocked onto the chip by CLK and becomes active after a pipeline delay of four

LOAD I This input becomes active after a pipeline delay of ﬁve clocks. When low, the feedback in the phase

OUT0-11 O Output data. OUT0 is LSB. Unsigned.

All inputs are TTL level, with the exception of CLK. Overline designates active low signals.

+5V power supply pin.

180, or 270 degrees can be selected as shown in Table 1.

the phase accumulator; a low selects the most signiﬁcant 32 bits.

ﬁrst; a high shifts in the data MSB ﬁrst.

four clocks.

clocks. When low, the frequency control word selected by SEL_L/M is transferred from the frequency register to the phase accumulator’s input register.

accumulator is zeroed.

3-196

HSP45102

PHASE OFFSET ADDER

R E G

R.P0-1 R.ENPHAC

R.TXFR

CLK

R.LOAD R E G

FREQUENCY

CONTROL

SECTION

64-BIT

SHIFT

REG

P0-1 ENPHAC TXFR LOAD CLK

SD SCLK SFTEN MSB/LSB

SEL_L/M

4-DLY

FIGURE 1. NCO-12 FUNCTIONAL BLOCK DIAGRAM

Functional Description

The NCO12 produces a 12-bit sinusoid whose frequency and phase are digitally controlled. The frequency of the sine wave is determined by one of two 32-bit words. Selection of the active word is made by output is controlled by the two-bit input P0-1, which is used to select a phase offset of 0, 90, 180, or 270 degrees.

As shown in the Block Diagram, the NCO12 consists of a Frequency Control Section, a Phase Accumulator, a Phase Offset Adder and a Sine ROM. The Frequency Control section serially loads the frequency control word into the frequency register. The Phase Accumulator and Phase Offset Adder compute the phase angle using the frequency control word and the two phase modulation inputs. The Sine ROM generates the sine of the computed phase angle. The format of the 12-bit output is offset binary.

Frequency Control Section

The Frequency Control Section shown in Figure 1 serially loads the frequency data into a 64-bit, bidirectional shift register. The shift direction is selected with the input. When this input is high, the frequency control word on the SD input is shifted into the register MSB ﬁrst. When MSB/LSB is low the data is shifted in LSB ﬁrst. The register shifts on the rising edge of SCLK when timing of these signals is shown in Figures 2A and 2B.

The 64 bits of the frequency register are sent to the Phase Accumulator Section where 32 bits are selected to control the frequency of the sinusoidal output.

Phase Accumulator Section

The phase accumulator and phase offset adder compute the phase of the sine wavefrom the frequency control word and

SEL_L/M. The phase of the

MSB/LSB

SFTEN is low. The

R.P0-1

13 MSBs

FRCTRL

0-31

FRCTRL

32-63

(HIGH SELECTS FRCTRL0-31, LOW SELECTS FRCTRL32-63)

D D E R

0 1

/ CLK

‘0’

R.LOAD

ACCUMULATOR

MUX

R.TXFR

CLK

R E

INPUT

MUX

0 1

R E

SINE

ROM

A D D E R

R.ENPHAC CLK

PHASE ACCUMULATOR

CLK

2-DLY

R E G

the phase modulation bits P0-1. The architecture is shown in Figure 1. The most signiﬁcant 13 bits of the 32-bit phase accumulator are summed with the two-bit phase offset to generate the 13-bit phase input to the Sine Rom. A value of 0 corresponds to 0 corresponds to a value of 180

, a value of 1000 hexadecimal

The phase accumulator advances the phase by the amount programmed into the frequency control register. The output frequency is equal to:

N INT

× 232⁄(), or=

CLK



OUT

---------------





CLK

where N is the 32 bits of frequency control word that is programmed. INT[•] is the integer of the computation. For example,if the control wordis 20000000 hexadecimaland the clock frequency is 30MHz, then the output frequency would be F

/8, or 3.75MHz.

CLK

The frequency control multiplexer selects the least signiﬁcant 32 bits from the 64-bit frequency control register when

SEL_L/M is high, and the most signiﬁcant 32 bits

when

SEL_L/M is low. When only one frequency word is

desired,

SEL_L/M and MSB/LSB must be either both high or both low. This is due to the fact that when a frequency control word is loaded into the shift register LSB ﬁrst, it enters through the most signiﬁcant bit of the register. After 32 bits have been shifted in, they will reside in the 32 most signiﬁcant bits of the 64-bit register.

When

TXFR is asserted, the 32 bits selected by the frequency

controlmultiplex erare clockedinto the phase accumulatorinput

OUT0-11

R E G

(EQ. 1)

(EQ. 2)

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