Wideband Balun-LNA Employing gm-Boosting Feedback Technique and CBLD Circuit for Digital Televisions Tuner Application

A balun Low Noise Amplifier (Balun-LNA) with technique of gm-boosting feedback and a modified current bleeding (CBLD) circuit is proposed for application in the tuner of digital television (DTV) and other wideband radio and microwave receivers. Using the technique of gm-boosting feedback causes input impedance matching to not just depend on the CG transistor, and input impedance matching is satisfied by the transconductance of CG and CS transistors. Therefore, the transconductance of the CG transistor increases to boost the differential voltage gain of Balun-LNA and decrease its NF. Also, a modified current bleeding circuit is used in the CS stage in order to make the CS transistor have higher transconductance and its output current be identical to the output current of the CG stage. To compensate for having identical output currents, symmetrical loads are used in differential output so that they cause the gain and phase balance at the differential output. This Balun-LNA is built on ۹۰-nm CMOS technology and operates in the digital television frequency band of ۴۸ to ۸۶۴ MHz. This Balun-LNA achieves a maximum differential voltage gain of ۲۴ dB, an input return loss of less than -۱۰ dB, and a minimum NF of ۵ dB. This Balun-LNA works at ۲.۸ v nominal supply voltage and consumes the power of ۲.۵ mW.

کلیدواژه ها:

Balanced output ، Balun-LNA ، low power consumption ، Noise Cancelling ، Symmetrical loads ، Digital television tuner