This paper describes 2.4-GHz-band front-end building circuits--a down conversion mixer (DCM), a dual-modulus divide-by-4/5 prescaler, a transmit/receive antenna switch (SW), a power amplifier (PA), and a low noise amplifier (LNA). They are fabricated using a standard bulk 0.18 µm CMOS process with a lower current consumption than bipolar circuits, and can operate at the low supply voltage of 1.8 V. Meshed-shielded pads are adopted for lower receiver circuit noise. Pads shielded by metals become cracked when they are bounded, therefore silicided active areas are used as shields instead of metals to avoid these cracks. The meshed shields achieve lower parasitic pad capacitors without parasitic resistors, and also act as dummy active areas. The proposed DCM has a high IP3 characteristic. The DCM has a cascode FET configuration and LO power is injected into the lower FET. By keeping the drain-source voltage of the upper transistor large, the nonlinearity of the drain-source transconductance is reduced and a low distortion DCM is realized. It achieves a higher input referred IP3 with a higher conversion gain for almost the same current consumption of a conventional single-balanced mixer. The output referred IP3 is higher 5.0 dB than the single-balanced mixer. The proposed dual-modulus prescaler employs a fully-differential technique to achieve stable operation. In order to avoid errors, the fully-differential circuit gives the logic voltage swing margins. In addition, the differential technique also reduces the noise effect from the supply voltage line because of the common-mode signal rejection. The maximum operating frequency is 3.0 GHz, and the one flip-flop power consumption normalized by the maximum operating frequency is 180 µW/GHz.

We present a multiband LTE SAW-less CMOS transmitter with source-follower-driven passive mixers, envelope-tracked RF-programmable gain amplifiers (RF-PGAs), and Marchand Baluns. A driver stage for passive mixers is realized by a source follower, which enables a quadrature modulator (QMOD) to achieve low noise performance at a 1.2 V supply and contributes to a small-area and low-power transmitter. An envelope-tracking technique is adopted to improve the linearity of RF-PGAs and obtain a better Evolved Universal Terrestrial Radio Access Adjacent Channel Leakage power Ratio (E-UTRA ACLR). The Marchand balun covers more frequency bands than a transformer and is more suitable for multiband operation. The proposed transmitter, which also includes digital-to-analog converters and a phase-locked loop, is implemented in a 65-nm CMOS process. The implemented transmitter achieves E-UTRA ACLR of less than -42 dBc and RX-band noise of less than -158 dBc/Hz in the frequency range of 700 MHz–2.6 GHz. These performances are good enough for multiband LTE and SAW-less operation.

This paper describes the behavior of voids that were formed due to electromigration and diffusion in the interconnections of gold during a DC bias tests of GaAs ICs to current densities in the interconnections of 0.67 106 A/cm2 to 1.27 106 A/cm2 in the high temperature range of 230 to 260. We have found that the voids were formed at the centers in the cross sections of the interconnections and that gold is left around the voids, which means current still flows after the void formation. We have carefully observed the movement of the anode and cathode side edge of the voids during the tests and found that edges moved toward the cathode, in the direction opposite to the electron flow. This direction is constant. Also, the voids are extended, which means that the velocity of the cathode side edge is greater than that of the anode side edge. The velocity of the edges almost proportionally increased with the current density. The constant edge movement direction and the velocity of the edge dependence on the current density suggest that one of the causes of the edge movement is electromigration. The velocity of the edge depends on the distance between the anode side edge of the void and the through hole. The velocity increases in accordance with a decrease in the distance. This means that one of the causes of the edge movement is the diffusion of gold atoms by a concentration and pressure gradient. The GaAs IC failed at almost the same time as the voids appeared. It is important for reliability to prevent the formation of voids caused by electromigration and diffusion.

This paper describes two kinds of on-chip matched low-noise/driver MMIC amplifiers (LN/D-As) suitable for 2.4-GHz and 5.2-GHz short-range wireless applications. The ICs are fabricated in a 0.18 µm bulk CMOS which has no extra processing steps for enhancing the RF performance. The successful use of the current-reuse topology and interdigitated capacitors (IDCs) enables sufficiently low-noise and high output power operations with low current dissipation despite the chip fabrication in the bulk CMOS leading to large RF substrate and conductor losses. The main measurement results of the two LN/D-As are as follows: a 3.8-dB noise figure (NF) and a 10.1-dB gain under the conditions of 1.8 V and 6 mA, a 3.4-dBm 1-dB gain compressed output power (P1dB) for a 2.4-V voltage supply and a 13-mA operating current for the 2.4-GHz LN/D-A, and a 4.9-dB NF and an 11.1-dB gain with a 1.8 V and 10 mA supply condition, a 2.3-dBm P1dB at 2.4 V and 16 mA for the 5.2-GHz LN/D-A. Both MMICs are suited for low-noise amplifiers and driver amplifiers in 2.4-GHz and 5.2-GHz low-cost, low-power wireless systems such as Bluetooth and hiperLAN.