(GHz SMT to DIP Adapters)
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 VCC and VEE pins are connected to the adapter VCC and VEE 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 VTT plane and decoupling capacitors for the VTT and VEE planes are connected to the VCC (ground) plane, all located directly below the device, as shown in Fig. 3B.
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.
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 VCC and multiple sites for connections to ground, and is optimized for RF applications. All other adapters provide sites for connections to VCC, VEE, and VTT and are suitable for general purpose logic or linear applications up to 3 GHz
Fig. 1B, SO8 Bottom
Fig. 2A, SO8RF Top
Fig. 2B, SO8RF Bottom
Fig.3A, SO8 Top
Fig.3B SO8 Bottom
Fig.4A SO8RF Top
Fig. 4B SO8RF Bottom