Takayuki Ikushima

A dual bias-feed circuit design for SiGe HBT low-noise linear amplifier

An SiGe HBT low-noise amplifier (LNA) with a novel diode/resistor dual base bias-feed circuit is described. The dual bias-feed circuit extends P1 dB without degradation of the noise figure (NF). In the small-signal region, a conventional resistor bias-feed circuit is a dominant base current source and, in the large-signal region, the diode turns on and the diode bias-feed circuit supplies the base current like a voltage source, which allows higher output power and linearity. In this paper, the operation principle of the dual bias-feed circuit is explained by using a virtual current source model, which indicates the increase of base current of the HBT in a large-signal region. The design method is also described for the idle current of the diode bias-feed circuit in a small-signal region from the points-of-view of NF and P1 dB. The effectiveness of the dual bias-feed circuit is evaluated by simulation and measurement. The fabricated 2-GHz-band dual bias-feed LNA has the P1 dB improvement of 5 dB and no degradation NF compared with the conventional resistor bias-feed LNA.

An even harmonic mixer using self-biased anti-parallel diode pair

This paper presents a novel even harmonic mixer using self-biased anti-parallel diode pair (APDP). Resistors for self-bias are employed in APDP, and voltage differences in D.C. arise at each diode when LO power is applied. As increasing of LO power, voltage differences become larger, so maximum voltages of LO wave added to each diode are almost constant and conversion loss of the mixer is kept constantly. In the developed L-band even harmonic mixer using self-biased APDP for a direct conversion receiver, fluctuation of voltage conversion gain is below 1 dB with LO power of from 0 dBm to 14 dBm.

Integrated even harmonic type direct conversion receiver for W-CDMA mobile terminals

This paper is the first demonstration of the overall performance of the integrated even harmonic type direct conversion receiver (EH-DCR) with the RAKE receiver. The configuration of the integrated EH-DCR and its evaluation results based on the 3GPP definition are indicated. The RX LTCC module with the SiGe RX-IC, and BiCMOS ABB-IC are developed to achieve high integration of the receiver with filters. The integrated EH-DCR with low second order distortion can achieve high sensitivity and selectivity of the W-CDMA receiver, even with interference due to the transmitting signal. Described evaluation results satisfy the specifications defined by 3GPP. This paper clarifies effectiveness of the integrated EH-DCR for the third generation mobile terminals.

Suppression of multi-path couplings in MCM with a flip-chipped SiGe-MMIC

Techniques to obtain a high isolation property in a multi-chip module (MCM) between pads of a SiGe-MMIC flip-chipped on a low temperature co-fired ceramic (LTCC) are discussed. In such an MCM, there are two coupling paths. One is a path through the LTCC and the other is a path through the MMIC. To improve the total isolation property, structures to reduce the two coupling paths are required because the paths of such leakage are not in series but in parallel. We examined the disposition of several kinds of ground patterns on the LTCC. Also, we devised a metal plate on a bias circuit as a shielding structure on the SiGe-MMIC. The effectiveness of the isolating structures was verified by measuring IIP2 in a receiver MCM with a direct conversion SiGe-MMIC. The IIP2 property has been improved successfully as well as the isolation property.