Tag Archives: IF

F1200 Low-noise Digital IF VGA with FlatNoise

The F1200 of an IDT is a digitally controlled intermediate frequency differential variable gain amplifier that adjusts the gain either dynamically or as a one-time channel gain setting. The device has extremely low noise figure over the entire gain control range. It is packaged in compact 5×5 Thin QFNs with 200 ohm differential input and output impedances for ease of integration into the receiver lineup with IF frequencies up to 300MHz.

The device has exceptional DNL and INL simplifying digital compensation. It has extremely low Harmonic, IM2, and IM3 distortion that is necessary to drive an ADC directly in an IF sub-sampling application. The F1200 acts to enhance system SNR when VGA gain is reduced. The F1200 noise figure (NF) degrades only slightly (NF slope ~ -0.16 dB/dB) over a 13 dB control range while holding the output IP3 approximately constant. The resultant improvement in noise can enhance the system SNR up to 2 decibels at low gain settings relative to a standard VGA.

This design is used in either transmitter or receiver to add an adjustable gain element to the signal chain by increasing or decreasing the attenuation value. Other applications include base station, diversity receivers, digital pre-distortion, μ-wave point-to-point radios and public safety receivers.

F1200 Low-noise Digital IF VGA with FlatNoise – [Link]

How a Diode Ring Mixer works | Mixer operation theory and measurement

This video describes how a classic double-balanced diode-ring mixer operates. Very basic mixer theory is quickly reviewed, which describes how the sum and difference of the LO (local oscillator) and RF (Radio Frequency) inputs are generated at the IF (intermediate frequency) output. It is also noted that the sum and differences of the harmonics of the LO and RF are also present at the IF output. Math waveforms on the oscilloscope are used to illustrate the operation of the mixer, and the actual waveforms from the mixer are compared to the math waveforms and the differences are discussed. A detailed description of the operation of the mixer is presented, including the switching action of the diodes. Finally, the frequency components are are expected from the mixer are shown on the spectrum analyzer.

How a Diode Ring Mixer works | Mixer operation theory and measurement – [Link]

VCO enables a hands-free car kit for cell phones


Locally broadcast your cell phone through FM band using MAX2606 from Maxim:

This design idea presents an integrated IF voltage-controlled oscillator (VCO) that can retransmit the audio signal from a cell phone to the FM broadcast band. By placing the cell phone’s speaker near the microphone, the user can use the phone as a hands-free device while driving.


VCO enables a hands-free car kit for cell phones – [Link]

Low-Cost Spectrum Analysers Feature 1.5 GHz Top End

The light weight, compact size and low cost DSA800 family of spectrum analyzers from Rigol Technologies feature digital IF technology to provide the reliability and performance necessary for RF applications. The spectrum analyzers have a frequency range of 9 kHz to 1.5 GHz with a typical displayed average noise level (DANL) of ‑135 dBm. SSB offset phase noise is typically -80 dBc/Hz at 10 kHz, and the resolution bandwidth is adjustable from 100 Hz to 1 MHz. A preamplifier and AM/FM demodulation are standard with this instrument. [via]

Low-Cost Spectrum Analysers Feature 1.5 GHz Top End – [Link]