A novel frequency-independent third-order intermodulation distortion cancellation technique for BJT amplifiers

Abstract

Abstract-Second-harmonic control is implemented in a balanced common-emitter configuration to facilitate frequency-independent third-order intermodulation distortion cancellation. Moreover, this circuit configuration facilitates a simultaneous match for either power and linearity or noise and linearity. Experiments demonstrated an improvement of over 15 dB in the output third-order intercept point while maintaining freedom in the choice of load and source impedance.

On the design of unilateral dual-loop feedback low-noise amplifiers with simultaneous noise, impedance, and IIP3 match

“…Normally, is expressed in terms of -parameters [10], however, for this work it is more convenient to express it in terms of the -parameters of the neutralized LNA [see (27) in the Appendix]: (6) Note that this gain definition is only valid for an unconditionally stable amplifier. Therefore, the stability criteria for unilateral gain should be satisfied: and…”

“…Recently, new design techniques were introduced for the linearization of bipolar transistor stages, which are based on the use of proper even harmonic terminations [5], [6]. The following nonlinear analysis shows how we obtain the required optimum out-of-band terminations for IM3 cancellation.…”

“…However, also for the configuration in [4], a tradeoff still exists between linearity, gain, and current level. To overcome these limitations, recently new circuit techniques were introduced to improve the linearity of bipolar transistors at low current levels by proper even harmonic control through the use of out-of-band terminations [5], [6]. These latter techniques, based on the controlled cancellation of third-order intermodulation (IM3) products, offer more circuit design freedom to avoid tradeoffs in bias and linearity.…”

Power amplifier PAE and ruggedness optimization by second-harmonic control

“…The simulation is performed using Agilent's Advance Design System (ADS); the active part is included through the mextram 503 model of the B6HFC bipolar transistor technology. Using an ideal transformer in our simulation we can decouple common-mode from differential signals [3]. The fundamental impedance at the input is set to a conjugate match to maximize the power transfer to the input of the active device and, consequently, enhance the gain.…”

“…The orthogonality between fundamental and second-order components allows a decoupling in the matching networks [3]. This makes it possible, in principle, to circumvent the limitations of the single-ended topology with respect to the dependency of the 2ndHS on varying load conditions.…”