Electronic Devices and Semiconductor Manufacturing Commons^™

Variable Attenuator Blends Dynamic Range, Linearity, Chin-Leong Lim

Chin-Leong Lim

A voltage variable attenuators (VVA) with compact dimensions and high linearity can be realized by connecting PIN diodes in the form of a π network. However this VVA's maximum frequency is limited to ~1 GHz because of signal leakage through the series diodes' parasitic capacitances. The ceiling frequency can significantly raised by resonating the parasitic capacitance with a parallel inductor. This technique has been previously demonstrated on a discrete design. To reduce component count and size, this work extends the technique to a standalone, highly-integrated module. This paper reports the performances achieved at 3.5 GHz.

The prototype's attenuation is adjustable …

Wideband Voltage Variable Attenuator With Fewer Components, Chin-Leong Lim

Chin-Leong Lim

RF/microwave amplifying devices have unit-to-unit gain variability. So, in some critical applications such as the low noise amplifier (LNA) in cellular basestations, the gain has to be adjusted in production using a voltage-variable attenuators (VVA). Constant impedance VVAs such as the PI and the bridged-TEE topologies require between 14 to 18 components, including 2 to 4 active devices, but their large dynamic (attenuation) range is wasted in this amplifier gain adjustment application. To create a more economical and smaller VVA for amplifier gain adjustment, we investigated a new circuit configuration comprising one active and four passive components. This paper describes …

Vva Extends Bw And Dynamic Range, Chin-Leong Lim

Chin-Leong Lim

Voltage-variable attenuators (VVAs) enable gain adjustment in a wide range of applications, including in cable-television (CATV), satellite-television (SATV) systems, and even test equipment and measurement systems. The PI VVA configuration using PIN diodes is ubiquitous in CATV and SATV systems owing to its low part count, small size, constant impedance, high linearity, and multi-decade bandwidth. Presently, this class of VVAs have been under severe miniaturization pressure in order to shrink end-product size. To create the industry's smallest CATV/SATV-suitable VVA, we integrated all necessary components into a multi-chip-on-board (MCOB) package measuring 3.8 x 3.8 x 1.0 mm (14 mm square footprint). …

Cut Part Count And Increase Dynamic Range In The Hybrid Coupled Attenuator, Chin-Leong Lim

Chin-Leong Lim

Modern digital modulation formats are generally phase-sensitive. Therefore, the variable attenuators in digital wireless equipment should exhibit minimal phase variation over attenuation. The hybrid coupled attenuator (HCA) has substantially less phase variation than the competing constant-impedance attenuators such as the Pi and the Bridged-T. At microwave frequencies, HCA implementations tend to suffer from reduced dynamic (attenuation) range due to component parasitics, especially when plastic-packaged PIN diodes are selected to lower cost. To maximize the dynamic range in a low-cost 1.9 GHz HCA , we first identified the critical components and then compensated for their deleterious effect. This paper describes the …

Rf Applications Of Pin Diodes, Chin-Leong Lim

Chin-Leong Lim

PIN diodes are the ubiquitous "nuts & screws" components that hold together RF equipment as varied as the television, radio, 2-way radios, WLAN equipment etc. This talk covers PIN diode characteristics and RF applications such as switches, attenuators and limiters. Performance improvement techniques will also be discussed.

Cut Loss In Low-Voltage, Wideband Pin Attenuators, Chin-Leong Lim

Chin-Leong Lim

Many RF applications, including Cable and Satellite TV (CATV / SATV) networks, rely on voltage-variable attenuators (VVAs) for gain adjustment. VVAs consisting of PIN diodes arranged as a PI network are popular in CATV / SATV service owing to their constant impedance, high linearity, multi-decade bandwidth, low part count and compactness. When fabricated from thick bulk PIN diodes for high linearity, the PI VVA configuration typically requires a 0-15V control range. But modern equipment typically operates at 5V or less. Capping the control voltage at 5V adversely raises the VVA's minimum attenuation. To enable low voltage operation without degrading the …

Diode Quad Is Foundation For Pin Diode Attenuator, Chin-Leong Lim

Chin-Leong Lim

Voltage-variable attenuators (VVAs) enable gain adjustment in a wide range of applications, including in cable-television (CATV), satellite-television (SATV) systems, and even test equipment and measurement systems. The PI VVA configuration using PIN diodes is ubiquitous in CATV and SATV systems owing to its low part count, small size, constant impedance, high linearity, and multi-decade bandwidth. Presently, there is a great pressure to miniaturize this VVA in order to shrink end-product size. To miniaturize this class of VVAs, we integrated four diodes into a five-pin, leadfree SOT-25 surface mount package. This paper describes the prototype VVA's design, fabrication and experimental results. …