Microwave Circuits Designs Lab. (MCDL)
1. Co-design of high power amplifier and Low noise amplifier
In RF front-end, power amplifier (PA) is typically followed by post-selection bandpass filter (BPF). Conventionally, power amplifier and other passive components such BPF, power divider are independently designed based on 50-Ω system impedance. In order to minimize overall system loss, the passive components such as BPF, power divider should de designed with arbitrary termination impedances so that PA and BPF can directly cascaded without additional loss of matching network (MN). This approach leads to reduce circuit complexity, circuit size, and enhance overall system efficiency.
To address these research issue, microwave circuit design laboratory (MCDL) focus on following research topics, but not limited to following research area.
1) Co-design of BPF and discrete high power amplifier (PA)/low noise amplifier (LNA)
2) Co-design of BPF and power divider
3) Wafer level internally matched high PA
Figure 1. Co-design of high power amplifier and LNA design and results.
Figure 2. Wafer-level X-band internally matched high power amplifier.
2. In-band full duplex and multi-functional non-reciprocal circuit
The capacity enhancement and efficient use of available spectrum resources have become crucial for next generation of communication system due to higher demand of data traffic. To overcome these problems, in-band full duplex (IBFD) communication system that allows transmit and receive signal simultaneously on same frequency and same time, one of potential candidate for next generation communication system. The major challenge for implementing IBFD is reducing the strong self-interference imposed on the received by leakage of transmitted signals. To suppress self-interference, non-reciprocal components such as circulator is widely used.
To address these research issues, Microwave circuit design laboratory (MCDL) focus on research topics listed below, but not limited to following technical areas.
1) High and wide RF self-interference cancellation (SIC) techniques
2) Co-design of magnet-less isolator and bandpass filter (non-reciprocal BPF), circulator
3) Magnet-less non-reciprocal power divider and antenna
Figure 3. Inband-full duplex and RF self-interference cancellation circuits.
Figure 4. Magnet-less non-reciprocal bandpass filter and frequency response.
3. Multi-band/multi-functional tunable filters
Multi-band/multi-functional RF/millimeter wave circuits are becoming a major trend due to their ability to cover different communication standards and functionality with a single device. This trend demands the development of tunable and reconfigurable multi-band/multi-mode filters that constitute a key component in the radio frequency (RF) front-ends.
To address these issues, MCDL focus on new research challenges of multi-band/multi-functional RF/millimeter wave filters including tunable multi-band center frequency and bandwidths, compact substate integrated waveguide (SIW) filters for next generation communication systems.
Figure 5. Multi-band tunable bandpass filters with tunable center frequency and bandwidth.
Figure 6. Compact substrate integrated waveguide (SIW) bandpass filters.
4. RFIC circuit design
Microwave/millimeter wave spectrums have wide variety of applications including wireless communication, biomedical, and sensing systems. Because of wider bandwidth of millimeter-wave spectrum, there are increasing applications of millimeter-wave integrated circuits for emerging next generation 5G and 6G wireless communication. Microwave circuit design laboratory (MCDL) focuses on integrated circuits and systems design at microwave and millimeter-wave frequency ranges in following technical areas.
1) Integrated RF front-end solution for microwave/millimeter-wave applications
2) CMOS high power amplifier for 5G wireless communication
3) CMOS RF energy harvesting, Negative group delay circuits
4) Compound semiconductor switches for 5G wireless Communication
Figure 7. CMOS Doherty power amplifier using variable Balun transformer and adaptive bias control of auxiliary amplifier.
Figure 8. Fully integrated CMOS power amplifier with programmable gain amplifier.
Figure 9. NB-IoT dual-band CMOS low noise amplifier with variable gain.
Figure 10. CMOS negative group delay circuit.