AD9953PCB datasheet(11/42 Pages) AD

tên linh kiện	AD9953PCB

Giải thích chi tiết về linh kiện	400 MSPS 14-Bit, 1.8V CMOS Direct Digital Synthesizer

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PRELIMINARY TECHNICAL DATA

AD9953

In certain applications it is desirable to force the output signal to ZERO phase. Simply setting the

FTW to 0 does not accomplish this. It only results in the DDS core holding its current phase value.

Thus, a control bit is required to force the Phase Accumulator output to zero.

At power up the Clear Phase Accumulator bit is set to logic one but the buffer memory for this bit

is cleared (logic zero). Therefore, upon power up, the phase accumulator will remain clear until the

first I/O UPDATE is issued.

Phase Truncation

The 32-bit phase values generated by the Phase Accumulator are truncated to 19 bits prior to the

COS(x) block. That is, the 19 most significant bits of phase are retained for subsequent

processing. This is typical of standard DDS architecture and is a trade off between hardware

complexity and spurious performance. It can be shown that 19-bit phase resolution is sufficient to

yield 14-bit amplitude resolution with an error of less than ½ LSB. The decision to truncate at 19

bits of phase guarantees the phase error of the COS(x) block to be less than the phase error

associated with the amplitude resolution of the 14-bit DAC.

Clock Input

The AD9953 supports various clock methodologies. Support for differential or single-ended input

clocks, enabling of an on-chip oscillator and/or phase-locked loop (PLL) multiplier are all

controlled via user programmable bits. The AD9953 may be configured in one of six operating

modes to generate the system clock. The modes are configured using the ClkModeSelect pin,

CFR1<4>, and CFR2<7:3>. Connecting the external pin ClkModeSelect to logic HIGH enables

the on-chip crystal oscillator circuit. With the on-chip oscillator enabled, users of the AD9953

connect an external crystal to the REFCLK and REFCLKB inputs to produce a low frequency

reference clock in the range of 20-30MHz. The signal generated by the oscillator is buffered before

it is delivered to the rest of the chip. This buffered signal is available via the crystal out pin. Bit

CFR1<4> can be used to enable or disable the buffer, turning on or off the system clock. The

oscillator itself is not powered down in order to avoid long start-up times associated with turning

on a crystal oscillator. Writing bit CFR2<1> to logic HIGH enables the crystal oscillator output

buffer. Logic LOW at CFR2<1> disables the oscillator output buffer.

Connecting ClkModeSelect to logic LOW disables the on-chip oscillator and the oscillator output

buffer. With the oscillator disabled an external oscillator must provide the REFCLK and/or

REFCLKB signals. For differential operation these pins are driven with complementary signals.

For single-ended operation a 0.1uF capacitor should be connected between the unused pin and the

positive power supply. With the capacitor in place the clock input pin bias voltage is 1.35V. In

addition, the PLL may be used to multiply the reference frequency by an integer value in the range

of the 4 to 20.

REV. PrB 1/30/03

Page 11

Analog Devices, Inc.

Số phần tương tự - AD9953PCB

nhà sản xuất	tên linh kiện	bảng dữ liệu	Giải thích chi tiết về linh kiện
Analog Devices	AD9953	648Kb / 32P	400MSPS, 14-Bit, 1.8 V CMOS Direct Digital Synthesizer
	AD9953YSV	574Kb / 32P	400 MSPS, 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. A
	AD9953YSV-REEL7	574Kb / 32P	400 MSPS, 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. A
	AD9953YSVZ	574Kb / 32P	400 MSPS, 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. A
	AD9953YSVZ	648Kb / 32P	400MSPS, 14-Bit, 1.8 V CMOS Direct Digital Synthesizer

More results

Mô tả tương tự - AD9953PCB

nhà sản xuất	tên linh kiện	bảng dữ liệu	Giải thích chi tiết về linh kiện
Analog Devices	AD9953YSVZ	574Kb / 32P	400 MSPS, 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. A
	AD9951	825Kb / 28P	400 MSPS 14-Bit, 1.8 V CMOS Direct Digital Synthesizer Rev. 0
	AD9954	1Mb / 36P	400 MSPS 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. 0
	AD9951	480Kb / 28P	400 MSPS 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. A
	AD9952	731Kb / 28P	400 MSPS 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. 0
	AD9952YSVZ	569Kb / 28P	400 MSPS 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. B
	AD9953	574Kb / 32P	400 MSPS, 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. A
	AD9954	472Kb / 40P	400 MSPS, 14-Bit, 1.8 V CMOS, Direct Digital Synthesizer REV. B
	AD9951YSVZ	480Kb / 28P	400 MSPS 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. A
	AD9952	569Kb / 28P	400 MSPS 14-Bit, 1.8 V CMOS Direct Digital Synthesizer REV. B

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