Gigadapters (GHz SMT to DIP Adapters) 

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Matched Impedance

The basic Gigadapter design was based on the concept of matched impedance. That is, controlled impedance I/O lines are provided for every device pin. Each adapter has a multi-layer pc board with a specific surface mount device footprint, such as an SO8, SO20 or PLCC28, etc., on one side of the pc board. On the other side, there are pads located strategically under the device footprint for mounting critical components, such as decoupling capacitors, termination resistors and other series and/or shunt components. These components have very short connections to the device footprint above via feed through holes, as shown in Fig.’s 3B and 4B.

Power and Ground Planes

Furthermore, each pc board has power and ground planes. These planes are connected to extra pins, in addition to the device pins, for connections to the motherboard, so that none of the device pins needs to be committed before a device is installed. In the SO8 and SO16 adapters, however, the device V_CC and V_EE pins are connected to the adapter V_CC and V_EE pins, respectively, through easily-cut short traces, so that these adapters can be converted for use with linear devices as well. Typical PC layout patterns for an SO8 adapter are shown in Fig.’s 1A through 2B, and the corresponding physical adapters with components installed on both sides of the adapters are shown in Fig.’s 3A through 4B.

General Purpose Adapters

In the general purpose adapters, controlled impedance I/O lines on top of the adapter board connect the device footprint to the adapter pins directly, as shown in Fig. 1A and Fig. 3A. On the bottom side, 50 Ω input termination resistors are connected to the V_TT plane and decoupling capacitors for the V_TT and V_EE planes are connected to the V_CC (ground) plane, all located directly below the device, as shown in Fig. 3B.

RF Adapters

In the RF adapter series, I/O lines on top of the adapter board connect the device footprint to a set of intermediate pads on the bottom through vias. These pads allows easy insertion of a series component, such as a coupling capacitor, a resistor or a zero W jumper, between the device footprint and the adapter pin. A center ground strip, as shown in Fig.’s 2B and 4B, enables insertion of shunt components between device pins and ground. The center ground strip is also connected to the adapter ground plane.

Available Models

We offer the following SO, SSOP, LCC/PLCC, and QFP/TQFP footprint adapters now, with more to come:

• SO Device Adapters--SO8, SO16, SO16RF, SO20, and SO20RF 
• SSOP Device Adapters-- SSO24RF, SSO28RF, and SSO30RF
• LCC/PLCC Device Adapters--PLCC20 and PLCC28
• QFP Device Adapters--QFP-32, QFP-44, QFP-48, QFP-52, and QFP-64.

The " RF" series provides V_CC and multiple sites for connections to ground, and is optimized for RF applications. All other adapters provide sites for connections to V_CC, V_EE, and V_TT and are suitable for general purpose logic or linear applications up to 3 GHz

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