TX ACLR Breakdown
TX ACLR TX is one of the most challenging (and rewarding) block in RFIC design, and ACLR is one of the key TX design spec. ACLR is a measure of out-of-band distortion (and noise) that leaks to the neighboring band. While IM3 is a great test for distortion, it leaves a lot to be desired […]
mm-wave PA Design
A sneak peak into the design of a 94GHz mm-Wave PA using Keysight ADS, Cadence and Sonnet.
TX IQ Mixer
TX IQ Mixer We want to upconvert our baseband signal, (omega_{bb}) , to an RF frequency, (omega_{lo}+omega_{bb}). The easiest and probably the only way alive of doing so is to multiply (omega_{bb}) signal with (omega_{lo}) signal. This works and generates two sidebands, (omega_{lo}+omega_{bb}) & (omega_{lo}-omega_{bb}). But in almost all of the applications today, you just […]
TX HRM Mixer
TX HRM Mixer Your mixer has two frequencies going in, (omega_{bb}) and (omega_{lo}), and you desire only one frequency coming out, (omega_{lo}+omega_{bb}). With the risk of stating the obvious, that is not what happens in real world. Your mixer outputs a lot more trash than you would have ever imagined. Some of it lies far […]
TX Mixer
TX Mixer Consider a typical TX with DAC (digital to analog converter), BBF (baseband filter and/or amplifier) and MIX (mixer) as shown in image below. Say DAC outputs a sinusoid signal. Let’s do some math to see what happens to the signal when it makes it to the TX output. $$ DAC,(t): Vcos(omega_{bb},t)$$ This signal […]
Counter Intermodulation Distortion aka 4FMODs
4FMODs and Counter IM3 New to transmitter design? Trying to understand what metrics are used by industry for transmitter design? You might have heard of primary 4FMOD (also called CIM3) and secondary 4FMOD (also called CIM5). Unlike traditional IM3 which is generated by intermodulation of two tones, CIM3 and CIM5 are primarily generated by distortion […]
Transmitter Specs
Transmitter Specs Having little exposure to Industry, academic researchers wonder if they are designing the transmitter for the right metrics? Are transmitter specs all about output power and linearity? And besides what metrics are used by industry to characterize linearity? If you have such questions, you have landed at correct place. Take a look at […]