Texas Instruments LMH6401IRMZT

Overview

LMH6401IRMZT from Texas Instruments is a fully-differential, digitally-controlled variable-gain amplifier (DVGA) designed for DC to 4.5 GHz RF/IF and high-speed time-domain applications. It delivers 26 dB maximum gain in 1-dB steps across –6 dB to +26 dB range, features 100 Ω differential input impedance, supports SPI interface control, and drives ultra-wideband ADCs with –63 dBc HD2/HD3 at 1 GHz.

For engineers reviewing the LMH6401IRMZT datasheet, LMH6401IRMZT pinout, LMH6401IRMZT application, or LMH6401IRMZT equivalent, this page provides verified specifications including 4.5 GHz small-signal bandwidth, 8 dB noise figure at 1 GHz, 43 dBm OIP3 at 200 MHz, differential output common-mode control via VOCM, and UQFN-16 package thermal metrics.

Technical Context

The LMH6401IRMZT integrates a high-linearity BiCMOS amplifier core with on-chip digital gain control logic and SPI interface circuitry. Its fully-differential architecture enables balanced signal paths with 47 dB output balance error suppression at 1 GHz and >38 dB CMRR across frequency.

Gain is adjusted via 5-bit SPI register writes controlling internal attenuation networks, achieving <1 ns gain step transition time and ±1 dB cumulative gain error over full 32-dB range. Power-down mode reduces quiescent current from 69 mA to 7 mA using either PD pin or SPI command.

Key Specifications

Pinout & Package

LMH6401IRMZT is housed in a 3.00 mm × 3.00 mm UQFN-16 package with wettable flanks, optimized for RF layout and thermal dissipation (RθJA = 78°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMH6401IRMZT, LMH6517RTVT trades 3.3 GHz bandwidth and 8 dB noise figure for lower power, while LMH6521RTVT offers higher linearity at 200 MHz but cannot support >1.2 GHz signal chains - making LMH6401IRMZT uniquely suitable for DC–4.5 GHz direct RF sampling.

Availability

LMH6401IRMZT is available at Aetrix Electronics and suitable for test and measurement instrumentation, ultra-wideband ADC drivers, communications receivers, defense and radar systems requiring stable component supply and guaranteed long-term availability.

Supply support for LMH6401IRMZT 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 LMH6401IRMZT belongs to TI's high-speed amplifier product line, engineered specifically for wideband RF/IF receiver front-ends demanding simultaneous high gain, low noise, and digital programmability in compact form factors.

FAQ

What is the maximum operating frequency of the LMH6401IRMZT?

The LMH6401IRMZT has a 4.5 GHz small-signal –3-dB bandwidth at 26-dB gain, verified per SBOS730A datasheet Figure 1. This enables use in direct RF sampling architectures up to S-band frequencies. Performance remains usable beyond 4.5 GHz with controlled gain roll-off, supporting applications such as 5G FR1 and radar waveform generation where flatness is less critical than absolute bandwidth.

Does the LMH6401IRMZT support single-supply operation?

Yes, the LMH6401IRMZT supports true single-supply operation at 5.0 V (VS+ = 5.0 V, VS– = GND), as confirmed in Section 7.3 Recommended Operating Conditions and Figure 11 of SBOS730A. Input common-mode range extends from (VS–) + 1.5 V to (VS+) – 1.5 V, and VOCM pin allows output common-mode adjustment to match downstream ADC requirements under single-rail biasing.

How does the SPI interface of the LMH6401IRMZT function?

The LMH6401IRMZT implements a 4-wire SPI interface (CS, SCLK, SDI, SDO) operating up to 50 MHz, enabling 5-bit gain register writes with <1 ns step transition time. The interface supports full-duplex communication and daisy-chaining; gain updates occur synchronously with SCLK edges, and status bits can be read back via SDO to verify register state after each write.

What is the noise figure of the LMH6401IRMZT and at what conditions is it specified?

The LMH6401IRMZT has an 8 dB noise figure at 1 GHz with RS = 100 Ω, measured per Section 7.5 Electrical Characteristics in SBOS730A. This value is representative of its performance when driving ultra-wideband ADCs with matched 100 Ω sources, and remains stable across temperature (±0.5 dB from –40°C to 85°C) and supply voltage (±0.3 dB from 4.0 V to 5.25 V).

Can the LMH6401IRMZT drive a 200 Ω differential ADC input directly?

Yes, the LMH6401IRMZT is explicitly characterized into a 200 Ω differential load (Ro = 20 Ω, VO = 2 VPPD) and delivers 6.0 VPPD maximum differential output swing. Its 20 Ω output resistance matches typical ADC driver interface requirements, and VOCM pin allows precise alignment of output common-mode voltage to the ADC's input specification - eliminating need for external level-shifting networks.