Chwan-Ying Lee

Method of creating local semi-insulating regions on silicon wafers for device isolation and realization of high-Q inductors

Penetrating proton beams from a compact ion cyclotron (diameter: 1.5 m, height: 2 m) were employed to create local semi-insulating regions within silicon substrates to facilitate device isolation in mixed-mode (analog-digital) integrated circuits (ICs) and realization of RF ICs with high-Q inductors. Experiments revealed that resistivity values of I M/spl Omega/-cm could be reached by practical proton fluences on silicon wafers of original resistivity of more than about 1 /spl Omega/-cm. Significant improvement was evidenced on Q values of irradiated inductors. Effect of reduced inductor metal conductivity from bombardment was over-shadowed by the more enhanced Q behavior, if the proton fluence is sufficiently large.

A harmonic injection-locked frequency divider in 0.18-/spl mu/m SiGe BiCMOS

A harmonic injection-locked frequency divider for high-speed applications is presented in this letter. In order to enhance the bandwidth of the high-order frequency division, a positive feedback is employed in the design of the subharmonic mixer loop. The proposed circuit is implemented in a 0.18-mum SiGe BiCMOS process. With a singled-ended super-harmonic input injection of 0dBm, the frequency divider exhibits a locking range of 350MHz (from 59.77 to 60.12GHz) for the divide-by-four frequency division while maintaining an output power of -16.6plusmn 0.5dBm within the entire frequency range. The frequency divider core consumes a dc power of 50mW from a 3.6-V supply voltage

A 60GHz transmitter with integrated antenna in 0.18/spl mu/m SiGe BiCMOS technology

A 60GHz SiGe HBT transmitter IC with integrated antenna in a standard-bulk 0.18mum SiGe BiCMOS process is reported. This chip is composed of a VCO, a sub-harmonic mixer, a PA, and a tapered-slot antenna, all with differential designs. The measured results show 15.8dBm output power and 20.2dB conversion gain with 281mWdc power consumption

Effects of Mechanical Uniaxial Stress on SiGe HBT Characteristics

In this work, we investigate the characteristics of collector current (I_C) and breakdown voltage (BV_CEO) of SiGe HBTs under the mechanical uniaxial stress by a four-point bending apparatus. DeltaI_c and DeltaBV_CEO is found to be strain-polarity dependent, and there is a trade-off between DeltaI _c and DeltaBV_CEO at the same stress condition

An Experimental Study on High-Frequency Substrate Noise Isolation in BiCMOS Technology

In this letter, four substrate noise isolation structures in standard 0.18-mum SiGe bipolar CMOS technology were investigated using S-parameter measurements. The experimental and simulated results on different isolation structures, such as triple-well p-n junction isolated walls, deep trench isolation, and double P+ guard-ring structures, are presented. Each element in the equivalent circuits has been calculated or fitted based on the parasitic resistance, capacitance, and physical dimensions using the device simulator MEDICI and the measured results of the test patterns. The proposed structure B significantly reduced substrate noise below -70 dB up to 20 GHz. The proposed structure C with an extra triple-well junction achieved the best isolation at the lower frequency range, in which |S21| was less than -71 dB from 50 MHz to 10.05 GHz, and -56 dB from 10.05 to 20.05 GHz. The measured results showed an excellent agreement with the calculations. Structure B is good enough and is recommended for a general-purpose RF circuit design, whereas structure C can be used in a highly sensitive RF circuit block below 10 GHz.

Frequency response improvement of 120 GHz f/sub T/ SiGe HBT by optimizing the contact configurations

For characterizing the frequency and power response of the SiGe HBT devices, the HBT devices with different base and collector contact configuration structure have been fabricated by using the 0.18 /spl mu/m high-speed SiGe BiCMOS technologies. In this work, we investigated three different types of layout with the same emitter area A/sub E/=0.3/spl times/10.16 /spl mu/m/sup 2/, including single base and single collector contact, double base and single collector contacts, and double base and double collector contacts. Regarding the maximum output power and cutoff frequency (f/sub T/), the double bases and double collectors structure is the optimized layout, which provides a 6.4 dBm maximum output power and a PAE of 40 % at 2.4 GHz. It also leads to achieve a higher cutoff frequency due to the reduction of contact resistances.

The high frequency and power performance of SiGe HBTs with SIC structure at cryogenic temperature

The high-frequency behavior and power capability of SiGe HBTs with selectively implanted collector structure have been measured at temperature between 77 and 350 K. Detailed analyses of temperature dependence on dc, high-frequency parameters, and power performances are presented. An HBT transit-time analysis is also described to find out the factors causing the increase in cutoff frequency (f/sub T/) at low temperature operation of different functionality of devices. In addition, the power capability of enhanced-breakdown device at liquid-nitrogen temperature is severely degraded.

A 1.8-V monolithic SiGe HBT power amplifier with a novel proposed linearizing bias circuit

In this work, we report a linearization technique by using an on-chip linearizer. The linearizer consists of a SiGe heterojunction bipolar transistors active bias circuit with a MOSFET feedback junction capacitor, which significantly improves the gain compression and phase distortion without additional dc consumption. The proposed circuit topology finds extensive applications in high efficiency and linearity power amplifier design. The power amplifier is implemented by using TSMC 0.18 mum SiGe HBT technology. The compact VBIC model of SiGe HBT was successfully established for the circuit design, and then a 2 GHz power amplifier was designed for demonstrating the circuit performances. The HBT power amplifier exhibits an output power over 20 dBm with a power-added efficiency higher than 42.4% under 1.8 volt operation

Geometry Effect on SiGe Heterojunction Bipolar Transistor Unit Cell for 1 W High-Efficiency RF Power Amplifier Applications

The effect of geometry on the RF power performance of silicon–germanium heterojunction bipolar transistor (SiGe HBT) unit cells is investigated using various emitter finger spacing (S). Two unit cells, namely, HBT-1 and HBT-2 with the same emitter area of 8×0.6×10 µm3 but with different S values are thoroughly discussed. The S values of HBT-1 and an HBT-2 are 2 and 5 µm, respectively. The obtained measurements, including DC characteristics and small- and large-signal performance characteristics of high-breakdown SiGe HBT unit cells, are presented. The HBT-1 in class-AB operations at 2.4 GHz achieves an output 1 dB compression point (OP1dB) of 16.0 dBm, a maximum output power of 17.4 dBm, and a peak-power added efficiency (PAE) of 59.1%. Under the same testing conditions, HBT-2 achieves an OP1dB of 19.6 dBm, a maximum output power of 20.6 dBm, and a PAE of 64.5%. HBT-2 yields significant improvements in all power performance parameters compared with HBT-1, such as 3.6 dB in an OP1dB, a maximum output power of 3.2 dB, a PAE of 5.4%, and an improvement in the power performance figure of merit (FOM) of approximately 50%, which is attributed to the fact that HBT-2 has a lower thermal effect than HBT-1. The thermal effect affects both DC and output power characteristics. A 1 W power device fabricated by combining eight HBT-2 unit cells achieves a power gain of 14.5 dB and a maximum PAE (PAEmax) of 75% in a class-AB operation at 2.4 GHz. The power density is calculated to be up to 2.6 mW/µm2. These results demonstrate that SiGe HBT technology has great potential for high-power amplifier applications.

The Analysis of Power and Linearity Characteristics of SiGe HBTs at Low Temperatures

This work investigates the temperature dependence, from 300K to 77K, of the output power, PAE, and linearity for SiGe HBTs with and without SIC. The NADC pi/4DQPSK signal is used to analyze the linearity of SiGe HBTs. For device without SIC, the heterojunction barrier effect becomes more propound, which seriously reduces the current gain and cutoff frequency at cryogenic temperatures. The output power, PAE and linearity at 2.4 GHz decrease conspicuously with decreasing operation temperatures. This barrier effect can be negligible in SiGe HBT with SIC and thus the device achieves better power and linearity performance at cryogenic temperatures