Kai-Siang Lan

6.3 mW 94 GHz CMOS Down-Conversion Mixer With 11.6 dB Gain and 54 dB LO-RF Isolation

A 94 GHz CMOS down-conversion mixer is reported. RF negative resistance compensation (NRC) technique, i.e., PMOS LC-oscillator-based RF transconductance (GM) stage load, is used to increase the output impedance and suppress the feedback capacitance Cgd of RF GM stage. As a result, conversion gain (CG), noise figure (NF) and LO-RF isolation of the mixer are enhanced. For frequencies of 80~110 GHz, the mixer consumes 6.3 mW and achieves excellent RF-port input reflection coefficient (S11) of -8.7~ -22 dB and LO-port input reflection coefficient (S22) of -10.3~-19.4 dB. In addition, the mixer achieves excellent CG of 4.1~11.6 dB, NF of 15.8~18.1 dB, and LO-RF isolation of 42.1~54 dB for frequencies of 80~110 GHz, one of the best CG, NF and LO-RF isolation results ever reported for a W-band CMOS down-conversion mixer.

High-performance elliptic dual balun for W-band CMOS transceiver

Two elliptic CMOS dual baluns for W-band (75–110 GHz) transceiver are reported. The input couple-line width of the first dual balun (i.e. dual balun A) is 4 µm. For contrast, the input couple-line width of the second dual balun (i.e. dual balun B) is 2 µm. The width of all the other couple-lines and all space of the two dual baluns is 2 µm. The dual balun can be applied to a power amplifier for four-way equal power dividing. Both the dual baluns occupy a small chip area of 0.0256 mm². For frequencies of 75∼110 GHz, dual balun A achieves S<inf>11</inf> of −10.1∼ −20.2 dB, S<inf>21</inf> of −7.6∼ −9.2 dB, S<inf>31</inf> of −8.5∼ −10.3 dB, S<inf>41</inf> of −7.4∼ −9 dB, S<inf>51</inf> of −9.2∼ −10.4 dB, magnitude of amplitude imbalance (MAI) of 0.42∼1.31 dB and phase difference (PD) of 180°∼ 186.3° for ports 2∼3, and MAI of 0.95∼2.4 dB and PD of 175.1°∼186.3° for ports 4∼5. In addition, dual balun B achieves S<inf>11</inf> of −10.1∼ −18.1 dB, S<inf>21</inf> of −7.8∼ −9 dB, S<inf>31</inf> of −7.8∼ −9.4 dB, S<inf>41</inf> of −7.5∼ −9.5 dB, S<inf>51</inf> of −7.8∼ −9.9 dB, MAI of 0∼0.75 dB and PD of 173.4°∼180° for ports 2∼3, and MAI of 0∼0.95 dB and PD of 173.4°∼181.3° for ports 4∼5, close to those of dual balun A. This means the elliptical dual balun has a large design margin for the input couple-line width. The prominent results of the elliptic dual balun indicate that it is suitable for W-band systems.

A low power and low phase-noise 91~96 GHz VCO in 90 nm CMOS

ABSTRACT This paper reports a 94 GHz CMOS voltage-controlled oscillator (VCO) using both the negative capacitance (NC) technique and series-peaking output power and phase noise (PN) enhancement technique. NC is achieved by adding two variable LC networks to the source nodes of the active circuit of the VCO. NMOSFET varicaps are adopted as the required capacitors of the LC networks. In comparison with the conventional one, the proposed active circuit substantially decreases the input capacitance (Cin) to zero or even a negative value. This leads to operation (or oscillation) frequency (OF) increase and tuning range (TR) enhancement of the VCO. The VCO dissipates 8.3 mW at 1 V supply. The measured TR of the VCO is 91~96 GHz, close to the simulated (92.1~96.7 GHz) and the calculated one (92.2~98.2 GHz). In addition, at 1 MHz offset from 95.16 GHz, the VCO attains an excellent PN of – 98.3 dBc/Hz. This leads to a figure-of-merit (FOM) of −188.5 dBc/Hz, a remarkable result for a V- or W-band CMOS VCO. The chip size of the VCO is 0.75 × 0.42 mm2, i.e. 0.315 mm2.

94 GHz CMOS down-conversion micromixer

A W-band (75∼110 GHz) down-conversion mixer for 94 GHz image radar sensors in 90 nm CMOS is reported. Micromixer-based gain-enhanced technique, i.e. inductive series-peaking gain-enhanced single-in differential-out (SIDO) class-AB RF GM stage, is used to increase the output impedance and suppress the feedback capacitance Cgd of RF GM stage. Hence, conversion gain (CG), noise figure (NF) and LO-RF isolation of the mixer can be enhanced. The mixer consumes 7.2 mW and achieves excellent RF-port input reflection coefficient of −10∼ −14.4 dB for frequencies of 81.4∼110 GHz. The corresponding −10 dB input matching bandwidth is greater than 28.6 GHz. In addition, for frequencies of 90∼96 GHz, the mixer achieves CG of 10.5∼12 dB (the corresponding 3-dB CG bandwidth is 22 GHz) and LO-RF isolation of 40.2∼46.2 dB, one of the best CG and LO-RF isolation results ever reported for a down-conversion mixer with operation frequency around 94 GHz. Furthermore, the mixer achieves an input third-order intercept point (IIP3) of 1 dBm at 94 GHz. These results demonstrate the proposed down-conversion mixer architecture is very promising for 94 GHz image radar sensors.

94 GHz VCO using negative capacitance technique

A 94 GHz voltage-controlled oscillator (VCO) using both LC-source-degeneration-based (LCSD-based) negative capacitance technique and series-peaking gain enhancement technique is demonstrated in a 90 nm CMOS process. The LCSD-based negative capacitance is made by adding two tunable LC tanks, which use NMOSFET varactors as the needed capacitors, to the source terminals of the cross-coupled transistor pair of the VCO. Compared with the traditional cross-coupled transistor pair, the proposed one significantly decreases the tunable equivalent parallel capacitance (CEQ) to zero and even a negative value. This in turn results in the increase of both the operation frequency and the tuning range of the VCO. The VCO draws 8.3 mA current from a 1 V power supply, i.e. it only consumes 8.3 mW. The VCO achieves a tuning range of 91∼96 GHz. In addition, the VCO achieves an excellent low phase-noise of −98.3 dBc/Hz at 1 MHz offset from 95.16 GHz. The corresponding FOM is −188.5 dBc/Hz, one of the best results ever reported for a V-or W-band CMOS VCO. The circuit occupies a small chip area of 0.75×0.42 mm2, i.e. 0.315 mm2, excluding the test pads.

One- and two-dimensional antenna arrays for microwave wireless power transfer (MWPT) systems

In this work, we demonstrate novel one- and two-dimensional antenna arrays for microwave wireless power transfer (MWPT) systems. The antenna array can be used as the MWPT receiving antenna of an integrated MWPT and Bluetooth (BLE) communication module (MWPT-BLE module) for smart CNC (computer numerical control) spindle incorporated with the cloud computing system SkyMars. The two-dimensional antenna array has n rows of 1×m one-dimensional array, in which each one-dimensional array is composed of multiple (m) differential feeding antenna units. Each differential feeding antenna unit has a microstrip antenna stripe. The stripe length is shorter than one wavelength to reduce the antenna area and to avoid being excited to a high-order mode. An inclination angle of the main beam aligns with the broadside, and the main beam is further concentrated and shrunk at the elevation direction. At the operation frequency of 9.9 GHz, the measured maximal E-plane gain is 9.9 dB. In addition, the measured maximal H-plane gain and beam width are 9.66 dB and 27.5°, respectively. The excellent performance of the antenna arrays indicates that they are suitable for MWPT systems.