Transconductance enhanced millimeter wave low-noise amplifier

Abstract

The invention belongs to the technical field of communication, and relates to a low noise amplifier (LNA), in particular to a transconductance enhanced millimeter wave low noise amplifier. According to the invention, a transconductance-enhanced differential cascode structure based on a transformer is adopted, so the expansibility is better; the application of each millimeter wave frequency band can be realized by tuning parameters of Lg, Ls, Cg and transistors M1, M2, M3 and M4; meanwhile, a capacitor Cg is introduced into the grid electrode of the cascode stage upper tube, so the feedback effect of the transconductance enhancement transformer is reduced, and the low-frequency stability is greatly improved; besides, in the aspect of matching, due to the inductance characteristic of the transformer, the imaginary part characteristic of impedance is improved, the result is more beneficial to impedance matching, and the loss of the matching circuit is reduced. In conclusion, the low-frequency feedback effect is ingeniously reduced, the low-frequency stability is greatly improved, the impedance value is moderate, the influence on inter-stage matching is small, and the low-frequency feedback circuit can be well applied to high-frequency bands such as a V band and a W band.

Description

technical field [0001] The invention belongs to the technical field of communication and relates to a low noise amplifier (LNA), in particular to a transconductance enhanced millimeter wave low noise amplifier. Background technique [0002] With the rapid development of communication technology, both industry and academia have put forward higher requirements for radar systems and communication systems; as a key module of the RF front-end, the performance of the low-noise amplifier will affect the noise performance and sensitivity of the entire receiver. Therefore, the LNA with high gain and low noise figure faces great challenges; especially as the frequency increases, the gain of the transistor decreases and the parasitic effect becomes more obvious, and the gain and noise performance will also deteriorate. [0003] In order to improve the performance of millimeter-wave LNA, researchers proposed some new structures. Commonly used transformer-based transconductance-enhanced...

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Problems solved by technology

[0005] (1) For example, in the W-band design, although the imaginary part of the output impedance of the circuit is smaller than that of the traditional cascode structure, it is still close to 100, which will lead to a relatively large loss in matching;

[0006] (2) Due to the characteristics of the transistor, when the single tube does not include a matching circuit, the gain at low frequencies must be greater than the gain at high frequencies. Therefore, when the frequency span of this circuit is large, the gain at low frequencies will be very high, which will greatly deteriorate its performance. stability;

[0007] (3) In terms of transistor size, due to the need to take into account the output impedance, we can only choose a larger size, which will result in lower gain and higher power consumption

[0008] In summary, traditional millimeter-wave LNAs usually use common-source, common-gate and cascode structures, which are suitable for lower frequency bands, such as Ku-band (12-18GHz), K-band (18- 27Hz), etc., and when the frequency rises to V-band (60-80GHz) and W-band (80-100GHz), the cut-off frequency f of the transistor t It will have a very obvious negative impact on the gain. Taking the 65nm CMOS process as an example, in the W-band, the maximum gain of a single transistor is only 7dB, and the gain of the common source and common gate is less than 10dB. , the imaginary part of the impedance is very large, and the matching circuit will bring huge losses. At the same time, in order to take into account the high-frequency gain, its low-frequency stability is very unsatisfactory

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