Sanghoon Sim

A CMOS UWB Pulse Generator for 6–10 GHz Applications

A CMOS ultra wideband (UWB) pulse generator with low energy dissipation and high peak amplitude is presented for 6-10 GHz applications. The pulse generator complies with the FCC spectral mask for indoor UWB systems. It consists of a glitch generator, a pulsed oscillator, and a pulse shaping filter. The pulsed oscillator is switched on by the glitch signal only for a short duration, so as to make a UWB pulse. For sub-nanosecond pulse generation, a pulsed oscillator with fast transient response is proposed. A pulse shaping filter makes the oscillator output fall into the FCC spectral mask. The pulse generator is fabricated using a 0.18 mum CMOS process. The core chip has a size of 0.11 mm2. It shows pulse duration of about 500 ps with -10 dB bandwidth of 4.5 GHz from 5.9 to 10.4 GHz. The energy consumption is 27.6 pJ per pulse with a peak-to-peak amplitude of 673 mV on a 50 Omega output load. The generated pulses are very coherent with 1.8 ps RMS jitter.

24 GHz circularly polarized Doppler radar with a single antenna

24 GHz circularly polarized Doppler front-end with a single antenna is developed. The radar system is composed of 24 GHz circularly polarized Doppler radar module, signal conditioning block, DAQ unit, and signal processing program. 24 GHz Doppler radar receiver front-end IC which is comprised of 3-stage LNA, single-ended mixer, and Lange coupler is fabricated with commercial InGaP/GaAs HBT technology. To reduce the chip size and suppress self-mixing, single-ended mixer which uses Tx leakage as a LO signal of the mixer is used. The operation of the developed radar front-end is demonstrated by measuring human vital signal. Compact size and high sensitivity can be achieved at the same time with the circularly polarized Doppler radar with a single antenna.

Cross-coupled differential oscillator MMICs with low phase-noise performance

LC-tank oscillators in the 5/spl sim/6 GHz frequency range have been designed and implemented in a commercial 0.6 /spl mu/m GaAs MESFET technology. One is a voltage-controlled oscillator (VCO), and the other is an oscillator without a controlling element. The output frequency range of the VCO is from 5.44 to 6.14 GHz, and the measured phase-noise is -101.67 dBc/Hz at an offset frequency of 600 KHz from the 5.44 GHz carrier. The phase-noise of the 6.44 GHz oscillator is -108 dBc/Hz at an offset frequency of 600 KHz, and the phase-noise curve, in the offset frequency range between 100 KHz and 1 MHz, shows a -20 dB/decade slope. These phase-noise characteristics are comparable to, or better than, those of the reported 5/spl sim/6 GHz-band CMOS oscillators. To our knowledge, this is the first GaAs MESFET-based oscillator which has a cross-coupled differential topology and a capacitive coupling feedback to suppress the up-conversion of 1/f noise. Also, it is first reported that the GaAs MESFET-based oscillator shows 1/f/sup 2/ phase-noise behavior across the offset frequency range from 100 KHz to 1 MHz.

A CMOS Direct Injection-Locked Frequency Divider With High Division Ratios

A CMOS injection-locked frequency divider (ILFD) with high division ratios and high frequency operation is presented. It consists of a ring oscillator and injection capacitors. An input signal is directly injected through the capacitors into the feedback nodes of the ring oscillator. The proposed ILFD is fabricated in a 0.18 mum CMOS process and has a chip core size of 68 mum times 70 mum. It shows multiple division ratios of 3, 6, and 9. The operation frequency is from 2.2 to 30.95 GHz. At the maximum operation frequency, the ILFD has a locking range of 260 MHz with an input power of less than 0.25 dBm, a division ratio of 9, and a power consumption of 12.5 mW. The locking range increases up to 3.2 GHz as the division ratio and the operation frequency decrease.

A CMOS Ultra-wideband radar transmitter with pulsed oscillator

A design of Ultra-wideband (UWB) radar transmitter is presented. The transmitter which uses a pulsed oscillator consists of pulse generator, switching buffers and control signal generator. The control signal generator includes modulators of binary-phase shift keying (BPSK) and pulse position modulation (PPM) for spreading the spectral lines. It is fabricated using 0.13 µm CMOS technology and the chip size is 910 × 485 µm2. The output spectrum is centered at the 22.0 GHz with the 10-dB bandwidth of 2.48 GHz and the pulse width of output pulse is tunable from 630ps to 830ps. Also, the BPSK and PPM modulations are confirmed. In conclusion, the generated pulse complies with FCCs spectral mask.

An X-Ku Band Distributed GaN LNA MMIC with High Gain

A high-gain wideband low noise amplifier (LNA) using 0.25-㎛ Gallium-Nitride (GaN) MMIC technology is presented. The LNA shows 8 ㎓ to 15 ㎓ operation by a distributed amplifier architecture and high gain with an additional common source amplifier as a mid-stage. The measurement results show a flat gain of 25.1±0.8 ㏈ and input and output matching of -12 ㏈ for all targeted frequencies. The measured minimum noise figure is 2.8 ㏈ at 12.6 ㎓ and below 3.6 ㏈ across all frequencies. It consumes 98 ㎃ with a 10-V supply. By adjusting the gate voltage of the mid-stage common source amplifier, the overall gain is controlled stably from 13 ㏈ to 24 ㏈ with no significant variations of the input and output matching.

An X-Band Switchless Bidirectional GaN MMIC Amplifier for Phased Array Systems

An X-Band switchless bidirectional amplifier (BDA) in a 0.25 μm gallium-nitride (GaN) on SiC process is introduced. The proposed bidirectional amplifier comprises of a 1 W power amplifier (PA) and a low noise amplifier (LNA) for T/R modules of phased array systems without any aid of switches. In receive mode, the BDA has flat gain of 20.2±1 dB and shows wideband input matching at 8 to 12 GHz. The minimum noise figure is 4.3 dB at 10.4 GHz and below 5 dB across the X-Band. In transmit mode, the small signal gain of the PA is 27±3 dB, its P1 dB is about 27 dBm, and its saturated output power is over 30 dBm at 8 to 12 GHz. The PA consumes 220 mA of quiescent current with 20 V power supply. While one mode is working, the other mode transistors are off and their parasitic capacitance has been already considered in design stage to minimize performance degradation and leakage. The total chip size is 2.5 mm×1.87 mm including pads.

CMOS-based Bi-directional T/R chipsets for phased array antenna

This paper presents the bi-directional CMOS-based T/R circuits. X-band bi-directional gain amplifier shows the gain of > 12 dB and the reverse isolation of > 35 dB at 8–12 GHz. X-band 5-bit phase shifter shows the insertion loss of < 17 dB, the RMS phase error of < 2.6°, and the RMS amplitude error of < 0.5 dB at 8–12 GHz. For wideband applications, true time delay circuit is developed to enable a time delay up to 198 ps with the LSB of 1.6 ps. The insertion loss of < 40 dB is achieved at 8–15 GHz. To compensate the losses of the TTD, the distributed bi-directional gain amplifier shows the gain of > 8.5 dB and the P1dB of 7 dBm at 8–15 GHz. The 6-bit digital step attenuator with the maximum attenuation of 31 dB shows the insertion loss of < 13 dB, the RMS phase error of < 3.5°, and the amplitude error of < 0.8 dB at DC-15 GHz.

A C-Band Oscillator MMIC with High Output Power, Low Harmonics, and Low Phase Noise using Passive Buffer

A passive buffer of an oscillator to obtain high output power, low harmonics and low phase noise is presented. A cross-coupled oscillator with the passive buffer is fabricated using InGaP/GaAs HBT technology. The oscillation frequency is 6.96 GHz. The 2nd harmonic suppression is -36.23dBc in the one-side output power 9.43 dBm. The phase noise is -121.33 dBc/Hz at 1MHz offset. The chip size is 0.81 times 0.63 mm2. The performances are compared with those of the previously reported oscillators