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JESD204B clock device targets LTE, GSM base stations

Posted: 08 Dec 2014 ?? ?Print Version ?Bookmark and Share

Keywords:Analog Devices? LTE? GSM? base station? clock?

Analog Devices Inc. (ADI) has announced a JESD204B clock and SYSREF generator aimed to support the clock requirements for LTE and multicarrier GSM base station designs, defence electronics systems, RF test instrumentation, and other emerging wideband RF GSPS data acquisition signal chains. The JESD204B interface was specifically developed to target high-data-rate system design needs, and the AD9528 clock device boasts functions that support and enhance the unique capabilities of that interface standard, indicated the company.

The use of the JESD204B standard for the high-speed converter-to-digital processer interface is becoming increasingly prevalent across many modern applications as data rates are being pushed into the multi-Gb/s range, and multi-channel synchronisation and data latency management are becoming a system necessity.


The AD9528 provides a low-power, multi-output, clock distribution function with low-jitter performance, along with an on-chip, two-stage PLL and VCO. The on-chip VCO tunes from 3.6-4GHz, with the input receivers and oscillator providing both single-ended and differential operation.

The clock device provides JESD204B-compatible subclass 1 SYSREF and deterministic latency clocking signals and supports a variety of options for SYSREF signal generation. The most basic is a simple buffer function wherein the user-provided SYSREF signal is fanned out to the SYSREF output pins. When provided with an external SYSREF source, the AD9528 is also capable of synchronising the SYSREF outputs to the clock outputs being generated internally, which is necessary to achieve accurate deterministic latency. The AD9528 is also capable of generating the SYSREF source internally. The AD9528 supports both continuous signal SYSREF generation and "n-shot" pulse generation. N-shot generation is vital in systems where a continuous signal might result in unwanted spurs in the output spectrum of the data converter being clocked.

When connected to a recovered system reference clock and a VCXO, the AD9528 generates 12 low-noise outputs with a range of 1-400MHz, and two high-speed outputs at up to 1.25GHz. The frequency and phase of one clock output relative to another clock output can be varied by means of a divider phase-select function that serves as a jitter-free, coarse timing adjustment in increments that are equal to half the period of the signal coming from the VCO output. The SYSREF signals each have additional phase offset capability making it easy to dial-in the optimal arrival time at each target device.

The AD9528BCPZ, offered in a 72-lead LFCSP package, is in full production and can be had for $8.25 per 1,000 pieces. The AD9528/PCBZ evaluation board is available for $190.

The AD9528 can be designed into wideband RF data acquisition applications with ADI's AD9680 dual-channel, 14bit, 1GSPS JESD204B ADC.

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