Texas Instruments VCA820IDGST

Overview

VCA820IDGST from Texas Instruments is a wideband, linear-in-dB voltage-controlled variable gain amplifier (VGA) with differential input and single-ended output. It delivers 150-MHz small-signal bandwidth, 137-MHz 5-V_PP large-signal bandwidth, 0.1-dB gain flatness to 28 MHz, 1700-V/μs slew rate, and >40-dB gain adjust range. It is used in AGC receivers requiring precise RSSI tracking and high-speed pulse amplitude compensation.

For engineers reviewing the VCA820IDGST datasheet, VCA820IDGST pinout, VCA820IDGST application, or VCA820IDGST equivalent, key selection criteria include gain linearity (±0.4 dB at 20 dB max gain), control voltage range (0–2 V for 40-dB range), differential input impedance (0.5 MΩ || 1 pF), output current capability (±160 mA), and SOIC-14 package thermal performance (R_θJA = 80°C/W).

Technical Context

The VCA820IDGST integrates two input buffers and a current-feedback output amplifier with a multiplier core, enabling dc-coupled operation without external buffering. Its gain control interface accepts 0–2 V analog voltage, producing linear-in-dB attenuation down 40 dB from the externally set maximum gain (e.g., +10 V/V = 20 dB).

Gain is configured via external resistors RG (200 Ω) and RF (1 kΩ) per typical 20-dB setup; common-mode rejection ratio is 60–80 dB over –40°C to +85°C; output drive supports 100-Ω loads with ±3.9-V swing and ±160-mA current.

Key Specifications

Pinout & Package

The VCA820IDGST is housed in a 14-pin SOIC (D) package measuring 8.65 mm × 3.91 mm, with exposed pad not present and RoHS-compliant lead finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar variable gain amplifier applications.

Compared with VCA820IDGST, VCA821IDGSR trades output drive and thermal robustness (R_θJA = 130°C/W) for higher bandwidth, while VCA822IDGST offers identical performance in the same SOIC-14 package with enhanced manufacturing consistency for high-volume production.

Availability

VCA820IDGST is available at Aetrix Electronics and suitable for AGC receivers, differential line receivers, pulse amplitude compensation systems, and programmable attenuators requiring stable component supply across industrial, test & measurement, and communications applications.

Supply support for VCA820IDGST includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company specializing in analog and embedded processing technologies, with leadership in high-performance signal chain and power management solutions.

The VCA820IDGST belongs to TI's wideband variable gain amplifier product line, designed specifically for precision analog gain control in RF, IF, and video signal paths where linear-in-dB response, high speed, and dc coupling are mandatory.

FAQ

What is the maximum gain-setting resistor value supported by the VCA820IDGST?

The VCA820IDGST supports gain-setting resistor (RG) values from 20 Ω to 2 kΩ, with recommended values between 200 Ω and 1.33 kΩ depending on desired maximum gain. At RG = 200 Ω and RF = 1 kΩ, the device achieves +10 V/V (20 dB) maximum gain. Exceeding 2 kΩ may reduce gain linearity and increase susceptibility to noise on the RG node. The VCA820IDGST datasheet specifies absolute maximum current through RG as ±2.55 mA.

Does the VCA820IDGST require external output filtering for 50-Ω system interfacing?

No, the VCA820IDGST does not require external output filtering when driving 50-Ω loads, provided proper board-level termination and layout practices are followed. Its output stage is specified for ±160 mA drive into 5 Ω, supporting direct 50-Ω matching with series or parallel termination. However, for optimal harmonic suppression above 100 MHz, a simple RC snubber (e.g., 10 Ω + 100 pF) at the VOUT pin is recommended per TI Application Report SBAA223.

Can the VCA820IDGST operate from a single +10-V supply?

No, the VCA820IDGST requires dual ±5-V supplies (±3.5 V minimum, ±6 V maximum) and is not rated for single-supply operation. Its internal architecture relies on symmetrical rail-to-rail headroom for differential input stage biasing and output swing. Attempting single-supply use (e.g., +10 V and GND) violates absolute maximum ratings and will result in undefined operation, input clipping, or permanent damage. For single-supply applications, consider TI's THS7374 or similar rail-to-rail VGA alternatives.

What is the typical settling time of the VCA820IDGST when stepping gain control voltage?

The VCA820IDGST exhibits 11 ns settling time to 0.01% for a full-scale gain control voltage step (e.g., 0 V → 2 V) under AVMAX = 20 dB conditions with RL = 100 Ω. This specification assumes ideal source impedance (<100 Ω) and proper decoupling. Settling time degrades slightly with heavier capacitive loading on the VG pin; TI recommends limiting VG node capacitance to <10 pF and using a low-impedance driver (e.g., BUF634) for sub-20-ns critical timing applications involving the VCA820IDGST.

How does the VCA820IDGST handle overdrive recovery when the input exceeds common-mode limits?

When the VCA820IDGST input exceeds its specified common-mode range (+1.6 V / –2.1 V at ±5 V supplies), the device enters a nonlinear recovery mode with typical overdrive recovery time of 40–60 ns, as characterized in Figure 48 of the SBOS395D datasheet. Recovery is limited by internal RG current saturation and does not latch. To avoid distortion, maintain input signals within the guaranteed linear range; for transient-tolerant designs, add clamping diodes (e.g., BAT54S) at +VIN/–VIN referenced to ±5 V rails. The VCA820IDGST itself contains no internal protection beyond ESD structures.