Analog Devices Inc. DC1861A

Overview

DC1861A from Analog Devices (formerly Linear Technology) is an evaluation board for the LTC5567 300MHz–4GHz active downconverting mixer IC. It implements a bandpass IF matching network with 8:1 transformer, supports 153MHz IF center frequency, delivers +26.9dBm IIP3 at 1950MHz RF, 1.9dB conversion gain, and 11.8dB noise figure, and is used in DPD observation receivers and wireless infrastructure.

For engineers reviewing the DC1861A datasheet, DC1861A pinout, DC1861A application, or DC1861A equivalent, this page provides verified layout details, test circuit configuration, IF/RF/LO matching component values, thermal performance data, and design guidance for high-linearity RF downconversion in 5G base station and CATV observation paths.

Technical Context

The DC1861A implements the standard downmixer test circuit from the LTC5567 datasheet (Figure 1), using Mini-Circuits TC8-1-10LN+ 4:1 IF transformer, 300nH 0603HP inductors (L1/L2), 330pF DC-blocking capacitors (C7/C8), and 3.01kΩ resistors (R1/R2) to establish a 400Ω differential IF output impedance. It supports both high-side and low-side LO injection.

Board-level RF input matching uses a 2.7pF capacitor (C3) for 1400–3000MHz operation; LO input matching uses 3.9pF (C5) for 1–4GHz; and the exposed pad (Pin 17) is soldered to PCB ground for thermal and electrical integrity. The board operates across –40°C to 105°C case temperature range.

Key Specifications

Availability

DC1861A is available at Aetrix Electronics and suitable for DPD observation receivers, wireless infrastructure receivers, and CATV infrastructure applications requiring stable component supply, rapid prototyping validation, and production-ready RF mixer reference designs.

Supply support for DC1861A 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

Analog Devices acquired Linear Technology in 2017 and maintains its high-performance RF and signal chain product lines with rigorous characterization and application support.

The DC1861A belongs to Linear Technology's evaluation board family for RF mixers, designed specifically to validate LTC5567 performance in wideband downconversion systems with minimal external component count and repeatable measurement accuracy.

FAQ

What is the primary function of the DC1861A evaluation board?

The DC1861A evaluation board is a fully assembled and tested platform for characterizing the LTC5567 active downconverting mixer IC. It implements the standard test circuit from the LTC5567 datasheet, including RF/LO input matching networks, differential IF output biasing, 4:1 transformer-based 50Ω single-ended IF output, and thermal grounding via exposed pad soldering. DC1861A enables immediate RF performance validation without custom layout.

Which IF frequencies does the DC1861A support out-of-the-box?

The DC1861A is configured for 153MHz IF center frequency using 300nH inductors (L1/L2) and 330pF DC-blocking capacitors (C7/C8), delivering 84–350MHz 1dB bandwidth per datasheet Figure 9. For other IF frequencies (e.g., 140MHz, 190MHz, 250MHz), users must replace L1/L2 with values specified in Table 4 of the LTC5567 datasheet - DC1861A does not include jumper options for alternate IF configurations.

Can the DC1861A be used for wideband differential IF output without the transformer?

Yes - the DC1861A layout allows removal of the TC8-1-10LN+ IF transformer (T1) to access the native differential IF+ and IF– outputs. With T1 removed and R1/R2 set to 249Ω (per datasheet TA01a), the board supports wideband 200Ω differential IF output up to 2.5GHz, enabling direct connection to differential amplifiers or filters. This configuration requires rework but preserves all RF/LO matching functionality.

What are the critical RF and LO matching components on the DC1861A?

The DC1861A uses C3 = 2.7pF for RF input matching (1400–3000MHz), C5 = 3.9pF for LO input matching (1–4GHz), and supports optional C4 and L3 for sub-500MHz RF extension. All matching components are 0402 AVX MLCCs. The LO input remains 50Ω matched even when the LTC5567 is disabled - a key feature validated in Figure 7 of the LTC5567 datasheet and implemented on DC1861A.

Does the DC1861A support both high-side and low-side LO injection?

Yes - the DC1861A supports both high-side and low-side LO injection as confirmed by the "LS, HS" notation in the matching table (Figure 1, datasheet page 10) and verified performance plots (G03–G08). The board's fixed matching network achieves >12dB RF return loss and >10dB LO return loss across 1400–3000MHz (RF) and 1–4GHz (LO) for either injection mode, enabling flexible system architecture testing with the same DC1861A hardware.