Spurious-free dynamic range (SFDR) is a key specification of radio receivers and spectrum analyzers, characterizing the maximum distance between signal and noise+distortion. SFDR is limited by the linearity (intercept point IIP3 mostly, sometimes IIP2) and the noise floor. As receivers already have low noise figure (NF) there is more room for improving the SFDR by increasing the linearity. As t...

A square-law harmonic-rejection mixer (SL-HRM) driven by a sine local oscillator (LO) is proposed for wideband and tunable rejection of all LO harmonics. The key performances including the gain, noise figure (NF), input-referred third-order intercept point (IIP3), and harmonic rejection ratio (HRR) with respect to the amplitude and purity of the sine-LO are analyzed. In the circuit level, the S...

For about a year I have been experimenting with extremely high intercept amplifiers using 2N5109 bipolar junction transistors (BJTs). These kinds of amplifiers, known as common base transformer feedback (CBTF) amplifiers, and also known as common base noiseless feedback amplifiers, if properly designed and used, offer MW DXers (and SW DXers, though their needs are not as extreme as MW DXers) am...

This paper presents a channel-select filter that employs an active-RC bi-quad structure for TV-tuner application. A design method to optimize the IIP3 of the bi-quad is developed. Multi-band selection and gain adjustment are implemented using switching resistors in the resistor array and capacitors in the capacitor array. Q-factor degradation is compensated by a tuning segmented resistor. A fee...

The design of a multi-band low noise amplifier (LNA) is the first obstacle towards the design of a multi-standard receiver. In this paper, an approach for the design of a multi-band LNA for DECT and Bluetooth is presented. The formula for a minimal noise factor of a LNA, that takes into account the finite quality factor of the inductors is derived and the full design procedure that facilitates ...