RF CW Signal Generator  Reference Design

The design is suitable for applications in test and measurement, wireless communications, military and aerospace, radar detection, and microwave backhaul.

Signal generators are essential instruments that produce repeating or non-repeating signals used for the development, troubleshooting, and repair of electronic or electroacoustic devices. An analog signal generator comprises several key components, including a reference section that provides a reference signal to the synthesizer. The synthesizer, typically a phase-locked loop (PLL), generates RF frequencies, while the output section improves the dynamic output power range.

The TIDA-00626 design by Texas Instruments (TI) addresses reference spur and in-band spurious (IBS) issues while optimizing system complexity by reducing size, power consumption, and cost. By using a programmable clock generator as a reference, spurs caused by OSCin can be mitigated. IBS can be reduced through the LMX2592’s internal doubler and dividers or by adjusting the reference clock settings. This design incorporates the LMK61E2, an ultra-low noise programmable reference clock, to minimize spurs without impacting the integrated noise of the LMX2592. The LMK61E2 features an internal loop filter that can be programmed to maintain noise levels within acceptable limits. 

– Advertisement –

This is a 9.8-GHz wideband, low phase noise, continuous wave (CW) RF signal generator that employs a versatile spur reduction technique. Its output level is adjustable from –31.5 dBm to 9.4 dBm in 0.5-dB increments. This signal generator can function as a local oscillator for applications such as analog and vector signal generators, as well as a clock generator for RF analog-to-digital converters (ADCs). The TIDA-00626 can be controlled via a PC using the TI USB2ANY interface or through a microcontroller, such as the MSP430F5529 LaunchPad™.

Key features include an integrated wideband frequency synthesizer with an output range from 20 MHz to 9.8 GHz, excellent phase noise performance with –111 dBc/Hz at a 100-kHz offset and –133 dBc/Hz at a 1-MHz offset at 6 GHz, and low in-band spurious levels at –75 dBc. It offers a programmable output level from –31.5 dBm to 9.4 dBm in 0.5-dB steps and fine output frequency resolution of 0.05 Hz. The LMX2592 is a low-noise, wideband RF PLL with an integrated voltage-controlled oscillator (VCO) that supports both fractional-N and integer-N modes with a 32-bit fractional divider for precise frequency selection. The LMK61E2 is an ultra-low jitter PLLatinum programmable oscillator with an integrated fractional-N frequency synthesizer. The LP38798-ADJ is a high-performance linear regulator supplying an 800-mA output current, while the LM2776 and TPS61170 provide voltage regulation and conversion solutions. The TI MSP430 family of ultra-low-power microcontrollers further enhances the flexibility and efficiency of the design.

– Advertisement –

TI has tested this reference design. It comes with a bill of materials (BOM), schematics, assembly drawing, printed circuit board (PCB) layout, and more. The company’s website has additional data about the reference design. To read more about this reference design, click here.